Ubuntu 24.04 STIG V1R1

Ubuntu 24.04 LTS must not have the "systemd-timesyncd" package installed.

STIG ID: UBTU-24-100010 | SRG: SRG-OS-000480-GPOS-00227 | Severity: low | CCI: CCI-000366 | Vulnerability Id: V-270645

Vulnerability Discussion

Check

Verify the "systemd-timesyncd" package is not installed with the following command:

$ dpkg -l | grep systemd-timesyncd

If the "systemd-timesyncd" package is installed, this is a finding.

Fix

The "systemd-timesyncd" package will be uninstalled as part of the "chrony" package install. Purge the remaining configuration files for "systemd-timesyncd" from Ubuntu 24.04 LTS:

$ sudo apt-get purge systemd-timesyncd

Ubuntu 24.04 LTS must not have the "ntp" package installed.

STIG ID: UBTU-24-100020 | SRG: SRG-OS-000480-GPOS-00227 | Severity: low | CCI: CCI-000366 | Vulnerability Id: V-270646

Vulnerability Discussion

Check

Verify the "ntp" package is not installed with the following command:

$ dpkg -l | grep ntp

If the "ntp" package is installed, this is a finding.

Fix

Uninstall the "ntp" package using the following command:

$ sudo apt remove ntp

If there are additional configuration files on the system that must be removed, the following command can be used instead:

$ sudo apt-get purge ntp

Ubuntu 24.04 LTS must not have the telnet package installed.

STIG ID: UBTU-24-100030 | SRG: SRG-OS-000074-GPOS-00042 | Severity: high | CCI: CCI-000197 | Vulnerability Id: V-270647

Vulnerability Discussion

Remote access services, such as those providing remote access to network devices and information systems, which lack automated control capabilities, increase risk and make remote user access management difficult at best.

Remote access is access to DOD nonpublic information systems by an authorized user (or an information system) communicating through an external, nonorganization-controlled network. Remote access methods include, for example, dial-up, broadband, and wireless.

Ubuntu 24.04 LTS functionality (e.g., RDP) must be capable of taking enforcement action if the audit reveals unauthorized activity. Automated control of remote access sessions allows organizations to ensure ongoing compliance with remote access policies by enforcing connection rules of remote access applications on a variety of information system components (e.g., servers, workstations, notebook computers, smartphones, and tablets).

Check

Verify the telnet package is not installed on Ubuntu 24.04 LTS with the following command:

$ dpkg -l | grep telnetd

If the telnetd package is installed, this is a finding.

Fix

Remove the telnet package from Ubuntu 24.04 LTS with the following command:

$ sudo apt remove telnetd

Ubuntu 24.04 LTS must not have the rsh-server package installed.

STIG ID: UBTU-24-100040 | SRG: SRG-OS-000095-GPOS-00049 | Severity: high | CCI: CCI-000381 | Vulnerability Id: V-270648

Vulnerability Discussion

It is detrimental for operating systems to provide, or install by default, functionality exceeding requirements or mission objectives. These unnecessary capabilities or services are often overlooked and therefore, may remain unsecured. They increase the risk to the platform by providing additional attack vectors.

Operating systems are capable of providing a wide variety of functions and services. Some of the functions and services, provided by default, may not be necessary to support essential organizational operations (e.g., key missions, functions).

Examples of nonessential capabilities include, but are not limited to, games, software packages, tools, and demonstration software, not related to requirements or providing a wide array of functionality not required for every mission, but which cannot be disabled.

Check

Verify the rsh-server package is installed with the following command:

$ dpkg -l | grep rsh-server

If the rsh-server package is installed, this is a finding.

Fix

Configure Ubuntu 24.04 LTS to disable nonessential capabilities by removing the rsh-server package from the system with the following command:

$ sudo apt remove rsh-server

Ubuntu 24.04 LTS must use a file integrity tool to verify correct operation of all security functions.

STIG ID: UBTU-24-100100 | SRG: SRG-OS-000445-GPOS-00199 | Severity: medium | CCI: CCI-002696 | Vulnerability Id: V-270649

Vulnerability Discussion

Without verification, security functions may not operate correctly and the failure may go unnoticed. Security function is defined as the hardware, software, and/or firmware of the information system responsible for enforcing the system security policy and supporting the isolation of code and data on which the protection is based. Security functionality includes, but is not limited to, establishing system accounts, configuring access authorizations (i.e., permissions, privileges), setting events to be audited, and setting intrusion detection parameters.

This requirement applies to Ubuntu 24.04 LTS performing security function verification/testing and/or systems and environments that require this functionality.

Check

Verify that Advanced Intrusion Detection Environment (AIDE) is installed and verifies the correct operation of all security functions with the following command:

$ dpkg -l | grep aide
ii aide 0.18.6-2build2 amd64 Advanced Intrusion Detection Environment - dynamic binary
ii aide-common 0.18.6-2build2 all Advanced Intrusion Detection Environment - Common files

If AIDE is not installed, ask the system administrator how file integrity checks are performed on the system.

If there is no application installed to perform integrity checks, this is a finding.

Fix

Install the "AIDE" file integrity package:

$ sudo apt install -y aide

Ubuntu 24.04 LTS must configure AIDE to preform file integrity checking on the file system.

STIG ID: UBTU-24-100110 | SRG: SRG-OS-000445-GPOS-00199 | Severity: medium | CCI: CCI-002696 | Vulnerability Id: V-270650

Vulnerability Discussion

Check

Note: If AIDE is not installed, this finding is not applicable.

Verify Advanced Intrusion Detection Environment (AIDE) is configured on the system by preforming a manual check:

$ sudo aide -c /etc/aide/aide.conf --check

Example output:
...
Start timestamp: 2024-10-30 14:22:38 -0400 (AIDE 0.18.6)
AIDE found differences between database and filesystem!!
...

If AIDE is being used for system file integrity checking and the command fails, this is a finding.

Fix

Initialize the AIDE package (this may take a few minutes):
$ sudo aideinit
Running aide --init...

The new database will need to be renamed to be read by AIDE:
$ sudo cp -p /var/lib/aide/aide.db.new /var/lib/aide/aide.db

Perform a manual check:
$ sudo aide -c /etc/aide/aide.conf --check

Example output:
...
Start timestamp: 2024-10-30 14:22:38 -0400 (AIDE 0.18.6)
AIDE found differences between database and filesystem!!
...

Done.

Ubuntu 24.04 LTS must be configured so that the script which runs each 30 days or less to check file integrity is the default one.

STIG ID: UBTU-24-100120 | SRG: SRG-OS-000446-GPOS-00200 | Severity: medium | CCI: CCI-002699 | Vulnerability Id: V-270651

Vulnerability Discussion

Without verification, security functions may not operate correctly and the failure may go unnoticed. Security function is defined as the hardware, software, and/or firmware of the information system responsible for enforcing the system security policy and supporting the isolation of code and data on which the protection is based. Security functionality includes, but is not limited to, establishing system accounts, configuring access authorizations (i.e., permissions, privileges), setting events to be audited, and setting intrusion detection parameters.

Notifications provided by information systems include, for example, electronic alerts to system administrators, messages to local computer consoles, and/or hardware indications, such as lights.

This requirement applies to Ubuntu 24.04 LTS performing security function verification/testing and/or systems and environments that require this functionality.

Check

Note: If AIDE is not installed, this finding is not applicable.

Check the AIDE configuration file integrity installed on the system (the default configuration file is located at /etc/aide/aide.conf or in /etc/aide/aide.conf.d/) with the following command:
$ sudo sha256sum /etc/aide/aide.conf
f3bbea2552f2c5b475627850d8a5fba1659df6466986d5a18948d9821ecbe491 /etc/aide/aide.conf

Download the original aide-common package in the /tmp directory:
$ cd /tmp; apt download aide-common

Generate the checksum from the aide.conf file in the downloaded .deb package:
$ sudo dpkg-deb --fsys-tarfile /tmp/aide-common_0.18.6-2build2_all.deb | tar -xO ./usr/share/aide/config/aide/aide.conf | sha256sum
f3bbea2552f2c5b475627850d8a5fba1659df6466986d5a18948d9821ecbe491 -

If the checksums of the system file (/etc/aide/aide.conf) and the extracted file do not match, this is a finding.

To verify the frequency of the file integrity checks, inspect the contents of the scheduled jobs as follows:

Checking scheduled cron jobs:
$ grep -r aide /etc/cron* /etc/crontab
/etc/cron.daily/dailyaidecheck:SCRIPT="/usr/share/aide/bin/dailyaidecheck"

Checking the systemd timer (this will show when the next scheduled run occurs and the last time the AIDE check was triggered):
$ sudo systemctl list-timers | grep aide
Thu 2024-10-31 02:01:58 EDT 10h Wed 2024-10-30 13:47:41 EDT - dailyaidecheck.timer dailyaidecheck.service

The contents of these files can be inspected with the following commands:
$ sudo systemctl cat dailyaidecheck.timer
$ sudo systemctl cat dailyaidecheck.service

If there is no AIDE script file in the cron directories or in the systemd timer, this is a finding.

Fix

The cron file for AIDE is fairly complex as it creates the report. This file is installed with the "aide-common" package, and the default can be restored by copying it from the package:

Download the original package to the /tmp dir:

$ cd /tmp; apt download aide-common

Extract the aide script to its original place:

$ dpkg-deb --fsys-tarfile /tmp/aide-common_*.deb | sudo tar -x --wildcards ./usr/share/aide/config/cron.daily/dailyaidecheck* -C /

Copy it to the cron.daily directory:

$ sudo cp -f /usr/share/aide/config/cron.daily/aide /etc/cron.daily/dailyaidecheck*

Ubuntu 24.04 LTS must notify designated personnel if baseline configurations are changed in an unauthorized manner. The file integrity tool must notify the system administrator (SA) when changes to the baseline configuration or anomalies in the operation of any security functions are discovered.

STIG ID: UBTU-24-100130 | SRG: SRG-OS-000447-GPOS-00201 | Severity: medium | CCI: CCI-002702,CCI-001744 | Vulnerability Id: V-270652

Vulnerability Discussion

Unauthorized changes to the baseline configuration could make the system vulnerable to various attacks or allow unauthorized access to Ubuntu 24.04 LTS. Changes to Ubuntu 24.04 LTS configurations can have unintended side effects, some of which may be relevant to security.

Detecting such changes and providing an automated response can help avoid unintended, negative consequences that could ultimately affect the security state of Ubuntu 24.04 LTS. Ubuntu 24.04 LTS' IMO/information system security officer (ISSO) and SAs must be notified via email and/or monitoring system trap when there is an unauthorized modification of a configuration item.

Satisfies: SRG-OS-000447-GPOS-00201, SRG-OS-000363-GPOS-00150

Check

Verify that Advanced Intrusion Detection Environment (AIDE) notifies the SA when anomalies in the operation of any security functions are discovered with the following command:

$ grep SILENTREPORTS /etc/default/aide
SILENTREPORTS=no

If "SILENTREPORTS" is set to "yes", is commented out, or is missing, this is a finding.

Fix

Configure Ubuntu 24.04 LTS to notify designated personnel if baseline configurations are changed in an unauthorized manner.

Modify the "SILENTREPORTS" parameter in the "/etc/default/aide" file with a value of "no" if it does not already exist as follows:

SILENTREPORTS=no

Ubuntu 24.04 LTS must be configured to preserve log records from failure events.

STIG ID: UBTU-24-100200 | SRG: SRG-OS-000269-GPOS-00103 | Severity: medium | CCI: CCI-001665 | Vulnerability Id: V-270653

Vulnerability Discussion

Failure to a known state can address safety or security in accordance with the mission/business needs of the organization. Failure to a known secure state helps prevent a loss of confidentiality, integrity, or availability in the event of a failure of the information system or a component of the system.

Preserving operating system state information helps to facilitate operating system restart and return to the operational mode of the organization with least disruption to mission/business processes.

Check

Verify the log service is installed properly with the following command:

$ dpkg -l | grep rsyslog
ii rsyslog 8.2312.0-3ubuntu9 amd64 reliable system and kernel logging daemon

If the "rsyslog" package is not installed, this is a finding.

Check that the log service is enabled with the following command:

$ systemctl is-enabled rsyslog
enabled

If the command above returns "disabled", this is a finding.

Check that the log service is properly running and active on the system with the following command:

$ systemctl is-active rsyslog
active

If the command above returns "inactive", this is a finding.

Fix

Configure the log service to collect failure events.

Install the log service (if the log service is not already installed) with the following command:

$ sudo apt install -y rsyslog

Enable the log service with the following command:

$ sudo systemctl enable --now rsyslog

Ubuntu 24.04 LTS must have an application firewall installed in order to control remote access methods.

STIG ID: UBTU-24-100300 | SRG: SRG-OS-000297-GPOS-00115 | Severity: medium | CCI: CCI-002314 | Vulnerability Id: V-270654

Vulnerability Discussion

Remote access services, such as those providing remote access to network devices and information systems, which lack automated control capabilities, increase risk, and make remote user access management difficult at best.

Remote access is access to DOD nonpublic information systems by an authorized user (or an information system) communicating through an external, nonorganization-controlled network. Remote access methods include, for example, dial-up, broadband, and wireless.

Ubuntu 24.04 LTS functionality (e.g., RDP) must be capable of taking enforcement action if the audit reveals unauthorized activity. Automated control of remote access sessions allows organizations to ensure ongoing compliance with remote access policies by enforcing connection rules of remote access applications on a variety of information system components (e.g., servers, workstations, notebook computers, smartphones, and tablets).

Check

Verify that the Uncomplicated Firewall (ufw) is installed with the following command:

$ dpkg -l | grep ufw
ii ufw 0.36.2-6 all program for managing a Netfilter firewall

If the "ufw" package is not installed, ask the system administrator if another application firewall is installed.

If no application firewall is installed, this is a finding.

Fix

Install the ufw by using the following command:

$ sudo apt install -y ufw

Ubuntu 24.04 LTS must enable and run the Uncomplicated Firewall (ufw).

STIG ID: UBTU-24-100310 | SRG: SRG-OS-000297-GPOS-00115 | Severity: medium | CCI: CCI-002314 | Vulnerability Id: V-270655

Vulnerability Discussion

Check

Verify the ufw is enabled on the system with the following command:

$ sudo ufw status
Status: active

If the above command returns the status as "inactive" or any type of error, this is a finding.

If the ufw is not installed, ask the system administrator if another application firewall is installed. If a different firewall is active on the system, this is not a finding.

Fix

Enable the ufw by using the following command:

$ sudo ufw enable

Note: Enabling the firewall will potentially disrupt ssh sessions.

Ubuntu 24.04 LTS must have the "auditd" package installed.

STIG ID: UBTU-24-100400 | SRG: SRG-OS-000365-GPOS-00152 | Severity: medium | CCI: CCI-003938,CCI-001914,CCI-000169,CCI-000172,CCI-000135,CCI-000130,CCI-000131,CCI-000132,CCI-000133,CCI-000134,CCI-000154,CCI-000158,CCI-001876,CCI-001875,CCI-001877,CCI-001878,CCI-001879,CCI-001880,CCI-001881,CCI-001882 | Vulnerability Id: V-270656

Vulnerability Discussion

Without establishing the when, where, type, source, and outcome of events that occurred, it would be difficult to establish, correlate, and investigate the events leading up to an outage or attack.

Without the capability to generate audit records, it would be difficult to establish, correlate, and investigate the events relating to an incident or identify those responsible for one.

Audit record content that may be necessary to satisfy this requirement includes, for example, time stamps, source and destination addresses, user/process identifiers, event descriptions, success/fail indications, filenames involved, and access control or flow control rules invoked.

Reconstruction of harmful events or forensic analysis is not possible if audit records do not contain enough information.

Successful incident response and auditing relies on timely, accurate system information and analysis to allow the organization to identify and respond to potential incidents in a proficient manner. If Ubuntu 24.04 LTS does not provide the ability to centrally review Ubuntu 24.04 LTS logs, forensic analysis is negatively impacted.

Associating event types with detected events in Ubuntu 24.04 LTS audit logs provides a means of investigating an attack; recognizing resource utilization or capacity thresholds; or identifying an improperly configured operating system.

Satisfies: SRG-OS-000365-GPOS-00152, SRG-OS-000337-GPOS-00129, SRG-OS-000062-GPOS-00031, SRG-OS-000475-GPOS-00220, SRG-OS-000042-GPOS-00020, SRG-OS-000042-GPOS-00021, SRG-OS-000037-GPOS-00015, SRG-OS-000038-GPOS-00016, SRG-OS-000039-GPOS-00017, SRG-OS-000040-GPOS-00018, SRG-OS-000041-GPOS-00019, SRG-OS-000051-GPOS-00024, SRG-OS-000054-GPOS-00025, SRG-OS-000122-GPOS-00063, SRG-OS-000348-GPOS-00136, SRG-OS-000349-GPOS-00137, SRG-OS-000350-GPOS-00138, SRG-OS-000351-GPOS-00139, SRG-OS-000352-GPOS-00140, SRG-OS-000353-GPOS-00141, SRG-OS-000354-GPOS-00142

Check

Verify the audit service is configured to produce audit records with the following command:

$ dpkg -l | grep auditd
ii auditd 1:3.0.7-1build1 amd64 User space tools for security auditing

If the "auditd" package is not installed, this is a finding.

Fix

Configure the audit service to produce audit records containing the information needed to establish when (date and time) an event occurred.

Install the audit service (if the audit service is not already installed) with the following command:

$ sudo apt install -y auditd

Ubuntu 24.04 LTS must produce audit records and reports containing information to establish when, where, what type, the source, and the outcome for all DOD-defined auditable events and actions in near real time.

STIG ID: UBTU-24-100410 | SRG: SRG-OS-000365-GPOS-00152 | Severity: medium | CCI: CCI-003938,CCI-001914,CCI-000169,CCI-000172,CCI-000135,CCI-000130,CCI-000131,CCI-000132,CCI-000133,CCI-000134,CCI-000154,CCI-000158,CCI-001876,CCI-001875,CCI-001877,CCI-001878,CCI-001879,CCI-001880,CCI-001881,CCI-001882 | Vulnerability Id: V-270657

Vulnerability Discussion

Check

Verify the audit service is enabled with the following command:

$ systemctl is-enabled auditd.service
enabled

If the command above returns "disabled", this is a finding.

Verify the audit service is properly running and active on the system with the following command:

$ systemctl is-active auditd.service
active

If the command above returns "inactive", this is a finding.

Fix

Configure the audit service to produce audit records containing the information needed to establish when (date and time) an event occurred.

Enable the audit service with the following command:

$ sudo systemctl enable auditd.service

To reload the rules file, issue the following command:

$ sudo augenrules --load

Ubuntu 24.04 LTS audit event multiplexor must be configured to offload audit logs onto a different system or storage media from the system being audited.

STIG ID: UBTU-24-100450 | SRG: SRG-OS-000342-GPOS-00133 | Severity: low | CCI: CCI-001851 | Vulnerability Id: V-270658

Vulnerability Discussion

Information stored in one location is vulnerable to accidental or incidental deletion or alteration.

Offloading is a common process in information systems with limited audit storage capacity.

Satisfies: SRG-OS-000342-GPOS-00133, SRG-OS-000479-GPOS-00224

Check

Verify the audit event multiplexor is configured to offload audit records to a different system or storage media from the system being audited.

Check that audisp-remote plugin is installed:

$ dpkg -l | grep audispd-plugins
ii audispd-plugins 1:3.1.2-2.1build1.1 amd64 Plugins for the audit event dispatcher

If the packet is "not installed", this is a finding.

Check that the records are being offloaded to a remote server with the following command:

$ sudo grep -i active /etc/audit/plugins.d/au-remote.conf
active = yes

If "active" is not set to "yes", or the line is commented out, or is missing, this is a finding.

Check that audisp-remote plugin is configured to send audit logs to a different system:

$ sudo grep -i ^remote_server /etc/audit/audisp-remote.conf
remote_server = 192.168.122.126

If the "remote_server" parameter is not set, is set with a local address, or is set with an invalid address, this is a finding.

Fix

Configure the audit event multiplexor to offload audit records to a different system or storage media from the system being audited.

Install the audisp-remote plugin:

$ sudo apt install -y audispd-plugins

Set the audisp-remote plugin as active by editing the "/etc/audit/plugins.d/au-remote.conf" file:

$ sudo sed -i -E 's/active\s*=\s*no/active = yes/' /etc/audit/plugins.d/au-remote.conf

Set the address of the remote machine by editing the "/etc/audit/audisp-remote.conf" file:

$ sudo sed -i -E 's/(remote_server\s*=).*/\1 <remote addr>/' /etc/audit/audisp-remote.conf

where <remote addr> must be substituted by the address of the remote server receiving the audit log.

Make the audit service reload its configuration files:

$ sudo systemctl restart auditd.service

Ubuntu 24.04 LTS must have AppArmor installed.

STIG ID: UBTU-24-100500 | SRG: SRG-OS-000312-GPOS-00124 | Severity: medium | CCI: CCI-002165,CCI-001764,CCI-001774 | Vulnerability Id: V-270659

Vulnerability Discussion

Control of program execution is a mechanism used to prevent execution of unauthorized programs. Some operating systems may provide a capability that runs counter to the mission or provides users with functionality that exceeds mission requirements. This includes functions and services installed at Ubuntu 24.04 LTS-level.

Some of the programs, installed by default, may be harmful or may not be necessary to support essential organizational operations (e.g., key missions, functions). Removal of executable programs is not always possible; therefore, establishing a method of preventing program execution is critical to maintaining a secure system baseline.

Methods for complying with this requirement include restricting execution of programs in certain environments, while preventing execution in other environments; or limiting execution of certain program functionality based on organization-defined criteria (e.g., privileges, subnets, sandboxed environments, or roles).

Satisfies: SRG-OS-000312-GPOS-00124, SRG-OS-000368-GPOS-00154, SRG-OS-000370-GPOS-00155

Check

Verify Ubuntu 24.04 LTS has AppArmor installed with the following command:

$ dpkg -l | grep apparmor
ii apparmor 4.0.1really4.0.1-0ubuntu0.24.04.3 amd64 user-space parser utility for AppArmor
ii libapparmor1:amd64 4.0.1really4.0.1-0ubuntu0.24.04.3 amd64 changehat AppArmor library

If the AppArmor package is not installed, this is a finding.

Fix

Install "AppArmor" with the following command:

$ sudo apt install apparmor

Note: AppArmor must have properly configured profiles for applications and home directories. All configurations will be based on the actual system setup and organization and normally are on a per role basis. Refer to the AppArmor documentation for more information on configuring profiles.

Ubuntu 24.04 LTS must be configured to use AppArmor.

STIG ID: UBTU-24-100510 | SRG: SRG-OS-000368-GPOS-00154 | Severity: medium | CCI: CCI-001764,CCI-002235,CCI-001774 | Vulnerability Id: V-270660

Vulnerability Discussion

Control of program execution is a mechanism used to prevent execution of unauthorized programs. Some operating systems may provide a capability that runs counter to the mission or provides users with functionality that exceeds mission requirements. This includes functions and services installed at Ubuntu 24.04 LTS-level.

Some of the programs, installed by default, may be harmful or may not be necessary to support essential organizational operations (e.g., key missions, functions). Removal of executable programs is not always possible; therefore, establishing a method of preventing program execution is critical to maintaining a secure system baseline.

Methods for complying with this requirement include restricting execution of programs in certain environments, while preventing execution in other environments; or limiting execution of certain program functionality based on organization-defined criteria (e.g., privileges, subnets, sandboxed environments, or roles).

Satisfies: SRG-OS-000368-GPOS-00154, SRG-OS-000324-GPOS-00125, SRG-OS-000370-GPOS-00155

Check

Verify Ubuntu 24.04 LTS AppArmor active with the following commands:

$ systemctl is-active apparmor.service
active

If "active" is not returned, this is a finding.

$ systemctl is-enabled apparmor.service
enabled

If "enabled" is not returned, this is a finding.

Fix

Enable "apparmor" with the following command:

$ sudo systemctl enable apparmor.service

Start "apparmor" with the following command:

$ sudo systemctl start apparmor.service

Note: AppArmor must have properly configured profiles for applications and home directories. All configurations will be based on the actual system setup and organization and normally are on a per role basis. Refer to the AppArmor documentation for more information on configuring profiles.

Ubuntu 24.04 LTS must have the "libpam-pwquality" package installed.

STIG ID: UBTU-24-100600 | SRG: SRG-OS-000480-GPOS-00225 | Severity: medium | CCI: CCI-000366 | Vulnerability Id: V-270661

Vulnerability Discussion

Use of a complex password helps to increase the time and resources required to compromise the password. Password complexity, or strength, is a measure of the effectiveness of a password in resisting attempts at guessing and brute-force attacks. "pwquality" enforces complex password construction configuration and has the ability to limit brute-force attacks on the system.

Check

Verify Ubuntu 24.04 LTS has the "libpam-pwquality" package installed with the following command:

$ dpkg -l | grep libpam-pwquality
ii libpam-pwquality:amd64 1.4.5-3build1 amd64 PAM module to check password strength

If "libpam-pwquality" is not installed, this is a finding.

Fix

Install the "pam_pwquality" package by using the following command:

$ sudo apt install -y libpam-pwquality

Ubuntu 24.04 LTS must have the "SSSD" package installed.

STIG ID: UBTU-24-100650 | SRG: SRG-OS-000705-GPOS-00150 | Severity: medium | CCI: CCI-004046,CCI-004047,CCI-000765,CCI-000766 | Vulnerability Id: V-270662

Vulnerability Discussion

Without the use of multifactor authentication, the ease of access to privileged functions is greatly increased.

Multifactor authentication requires using two or more factors to achieve authentication.

Factors include:
1) Something a user knows (e.g., password/PIN);
2) Something a user has (e.g., cryptographic identification device, token); and
3) Something a user is (e.g., biometric).

A privileged account is defined as an information system account with authorizations of a privileged user.

Network access is defined as access to an information system by a user (or a process acting on behalf of a user) communicating through a network (e.g., local area network, wide area network, or the internet).

The DOD common access card (CAC) with DOD-approved PKI is an example of multifactor authentication.

Satisfies: SRG-OS-000705-GPOS-00150, SRG-OS-000105-GPOS-00052, SRG-OS-000106-GPOS-00053, SRG-OS-000107-GPOS-00054, SRG-OS-000108-GPOS-00055, SRG-OS-000375-GPOS-00160

Check

Verify Ubuntu 24.04 LTS has the packages required for multifactor authentication installed with the following command:

$ dpkg -l | grep sssd
ii sssd 2.9.4-1.1ubuntu6.1 amd64 System Security Services Daemon -- metapackage
ii sssd-ad 2.9.4-1.1ubuntu6.1 amd64 System Security Services Daemon -- Active Directory back end
ii sssd-ad-common 2.9.4-1.1ubuntu6.1 amd64 System Security Services Daemon -- PAC responder
ii sssd-common 2.9.4-1.1ubuntu6.1 amd64 System Security Services Daemon -- common files
ii sssd-ipa 2.9.4-1.1ubuntu6.1 amd64 System Security Services Daemon -- IPA back end
ii sssd-krb5 2.9.4-1.1ubuntu6.1 amd64 System Security Services Daemon -- Kerberos back end
ii sssd-krb5-common 2.9.4-1.1ubuntu6.1 amd64 System Security Services Daemon -- Kerberos helpers
ii sssd-ldap 2.9.4-1.1ubuntu6.1 amd64 System Security Services Daemon -- LDAP back end
ii sssd-proxy 2.9.4-1.1ubuntu6.1 amd64 System Security Services Daemon -- proxy back end

If the "sssd" package is not installed, this is a finding. The additional sssd components listed by the command may differ from configuration to configuration.

Ensure that "libpam-sss" (the PAM integration module for SSSD) is installed with the following command:

$ dpkg -l | grep libpam-sss
i libpam-sss:amd64 2.9.4-1.1ubuntu6.1 amd64 Pam module for the System Security Services Daemon

Ensure that "libnss-sss" (the NSS module for retrieving user and group information) is installed with the following command:

$ dpkg -l | grep libnss-sss
ii libnss-sss:amd64 2.9.4-1.1ubuntu6.1 amd64 Nss library for the System Security Services Daemon

Fix

Install the sssd.service and the required pam packages with the following commands:

$ sudo apt install -y sssd

$ sudo apt install -y libpam-sss

$ sudo apt install -y libnss-sss

Ubuntu 24.04 LTS must use the "SSSD" package for multifactor authentication services.

STIG ID: UBTU-24-100660 | SRG: SRG-OS-000705-GPOS-00150 | Severity: medium | CCI: CCI-004046,CCI-004047,CCI-000765,CCI-000766 | Vulnerability Id: V-270663

Vulnerability Discussion

Check

Verify the "sssd.service" is enabled and active with the following commands:

$ sudo systemctl is-enabled sssd
enabled

$ sudo systemctl is-active sssd
active

If "sssd.service" is not active or enabled, this is a finding.

Fix

Enable the "sssd.service to start automatically on reboot with the following command:

$ sudo systemctl enable sssd.service

ensure the "sssd" service is running

$ sudo systemctl start sssd.service

Ubuntu 24.04 LTS must have the "chrony" package installed.

STIG ID: UBTU-24-100700 | SRG: SRG-OS-000480-GPOS-00227 | Severity: low | CCI: CCI-000366 | Vulnerability Id: V-270664

Vulnerability Discussion

Check

Verify the "chrony" package is installed using the following command:

$ dpkg -l | grep chrony
ii chrony 4.5-1ubuntu4.1 amd64 Versatile implementation of the Network Time Protocol

If the "chrony" package is not installed, this is a finding.

Fix

Install the "chrony" network time protocol package using the following command:

$ sudo apt install -y chrony

Ubuntu 24.04 LTS must have SSH installed.

STIG ID: UBTU-24-100800 | SRG: SRG-OS-000423-GPOS-00187 | Severity: high | CCI: CCI-002418,CCI-002420,CCI-002422 | Vulnerability Id: V-270665

Vulnerability Discussion

Without protection of the transmitted information, confidentiality and integrity may be compromised because unprotected communications can be intercepted and either read or altered.

This requirement applies to both internal and external networks and all types of information system components from which information can be transmitted (e.g., servers, mobile devices, notebook computers, printers, copiers, scanners, and facsimile machines). Communication paths outside the physical protection of a controlled boundary are exposed to the possibility of interception and modification.

Protecting the confidentiality and integrity of organizational information can be accomplished by physical means (e.g., employing physical distribution systems) or by logical means (e.g., employing cryptographic techniques). If physical means of protection are employed, then logical means (cryptography) do not have to be employed, and vice versa.

Satisfies: SRG-OS-000423-GPOS-00187, SRG-OS-000425-GPOS-00189, SRG-OS-000426-GPOS-00190

Check

Verify the SSH package is installed with the following command:

$ dpkg -l | grep openssh
ii openssh-client 1:9.6p1-3ubuntu13.5 amd64 secure shell (SSH) client, for secure access to remote machines
ii openssh-server 1:9.6p1-3ubuntu13.5 amd64 secure shell (SSH) server, for secure access from remote machines
ii openssh-sftp-server 1:9.6p1-3ubuntu13.5 amd64 secure shell (SSH) sftp server module, for SFTP access from remote machines

If the "openssh" server package is not installed, this is a finding.

Fix

Install the "ssh" meta-package on the system with the following command:

$ sudo apt install -y ssh

Ubuntu 24.04 LTS must use SSH to protect the confidentiality and integrity of transmitted information.

STIG ID: UBTU-24-100810 | SRG: SRG-OS-000423-GPOS-00187 | Severity: high | CCI: CCI-002418,CCI-002420,CCI-002422 | Vulnerability Id: V-270666

Vulnerability Discussion

Check

Verify the "sshd.service" is enabled and active with the following commands:

$ sudo systemctl is-enabled ssh
enabled

$ sudo systemctl is-active ssh
active

If "ssh.service" is not active or loaded, this is a finding.

Fix

Enable the "ssh" service to start automatically on reboot with the following command:

$ sudo systemctl enable ssh.service

ensure the "ssh" service is running

$ sudo systemctl start ssh.service

Ubuntu 24.04 LTS must configure the SSH daemon to use FIPS 140-3 approved ciphers to prevent the unauthorized disclosure of information and/or detect changes to information during transmission.

STIG ID: UBTU-24-100820 | SRG: SRG-OS-000033-GPOS-00014 | Severity: medium | CCI: CCI-000068,CCI-003123,CCI-002421 | Vulnerability Id: V-270667

Vulnerability Discussion

Without cryptographic integrity protections, information can be altered by unauthorized users without detection.

Remote access (e.g., RDP) is access to DOD nonpublic information systems by an authorized user (or an information system) communicating through an external, nonorganization-controlled network. Remote access methods include, for example, dial-up, broadband, and wireless.

Nonlocal maintenance and diagnostic activities are those activities conducted by individuals communicating through a network, either an external network (e.g., the internet) or an internal network.

Local maintenance and diagnostic activities are those activities carried out by individuals physically present at the information system or information system component and not communicating across a network connection.

Encrypting information for transmission protects information from unauthorized disclosure and modification. Cryptographic mechanisms implemented to protect information integrity include, for example, cryptographic hash functions that have common application in digital signatures, checksums, and message authentication codes.

Satisfies: SRG-OS-000033-GPOS-00014, SRG-OS-000394-GPOS-00174, SRG-OS-000424-GPOS-00188

Check

Verify that the SSH daemon is configured to implement only FIPS-approved algorithms with the following command:

$ sudo grep -r 'Ciphers' /etc/ssh/sshd_config*
Ciphers aes256-gcm@openssh.com,aes128-gcm@openssh.com,aes256-ctr,aes128-ctr

If any ciphers other than "Ciphers aes256-gcm@openssh.com,aes128-gcm@openssh.com,aes256-ctr,aes128-ctr" are listed, the "Ciphers" keyword is missing, or the returned line is commented out, or if multiple conflicting ciphers are returned, this is a finding.

Fix

Configure Ubuntu 24.04 LTS to allow the SSH daemon to only implement FIPS-approved algorithms.

Add the following line (or modify the line to have the required value) to the "/etc/ssh/sshd_config" file (this file may be named differently or be in a different location if using a version of SSH that is provided by a third-party vendor):

Ciphers aes256-gcm@openssh.com,aes128-gcm@openssh.com,aes256-ctr,aes128-ctr

Restart the "sshd" service for changes to take effect:

$ sudo systemctl restart sshd

Ubuntu 24.04 LTS must configure the SSH daemon to use Message Authentication Codes (MACs) employing FIPS 140-3 approved cryptographic hashes to prevent the unauthorized disclosure of information and/or detect changes to information during transmission.

STIG ID: UBTU-24-100830 | SRG: SRG-OS-000250-GPOS-00093 | Severity: medium | CCI: CCI-001453,CCI-002890,CCI-002421 | Vulnerability Id: V-270668

Vulnerability Discussion

Without cryptographic integrity protections, information can be altered by unauthorized users without detection.

Remote access (e.g., RDP) is access to DOD nonpublic information systems by an authorized user (or an information system) communicating through an external, nonorganization-controlled network. Remote access methods include, for example, dial-up, broadband, and wireless. Nonlocal maintenance and diagnostic activities are those activities conducted by individuals communicating through a network, either an external network (e.g., the internet) or an internal network.

Local maintenance and diagnostic activities are those activities carried out by individuals physically present at the information system or information system component and not communicating across a network connection.

Encrypting information for transmission protects information from unauthorized disclosure and modification. Cryptographic mechanisms implemented to protect information integrity include, for example, cryptographic hash functions that have common application in digital signatures, checksums, and message authentication codes.

Satisfies: SRG-OS-000250-GPOS-00093, SRG-OS-000393-GPOS-00173, SRG-OS-000424-GPOS-00188

Check

Verify the SSH daemon is configured to only use MACs that employ FIPS 140-3 approved ciphers with the following command:

$ grep -irs macs /etc/ssh/sshd_config*
MACs hmac-sha2-512-etm@openssh.com,hmac-sha2-256-etm@openssh.com,hmac-sha2-512,hmac-sha2-256

If any algorithms other than "hmac-sha2-512-etm@openssh.com,hmac-sha2-256-etm@openssh.com,hmac-sha2-512,hmac-sha2-256" are listed, the returned line is commented out, or if conflicting results are returned, this is a finding.

Fix

Configure Ubuntu 24.04 LTS to allow the SSH daemon to only use MACs that employ FIPS 140-3 approved ciphers.

Add the following line (or modify the line to have the required value) to the "/etc/ssh/sshd_config" file (this file may be named differently or be in a different location if using a version of SSH that is provided by a third-party vendor):

MACs hmac-sha2-512-etm@openssh.com,hmac-sha2-256-etm@openssh.com,hmac-sha2-512,hmac-sha2-256

Restart the "sshd" service for changes to take effect:

$ sudo systemctl restart sshd

Ubuntu 24.04 LTS SSH server must be configured to use only FIPS 140-3 validated key exchange algorithms.

STIG ID: UBTU-24-100840 | SRG: SRG-OS-000033-GPOS-00014 | Severity: medium | CCI: CCI-000068 | Vulnerability Id: V-270669

Vulnerability Discussion

Without cryptographic integrity protections provided by FIPS-validated cryptographic algorithms, information can be viewed and altered by unauthorized users without detection.

The system will attempt to use the first algorithm presented by the client that matches the server list.

Check

Verify that the SSH daemon is configured to use only FIPS-validated key exchange algorithms with the following command:

$ sudo grep -ir kexalgorithms /etc/ssh/sshd_config*
KexAlgorithms ecdh-sha2-nistp521,ecdh-sha2-nistp384,ecdh-sha2-nistp256,diffie-hellman-group-exchange-sha256,diffie-hellman-group16-sha512,diffie-hellman-group14-sha256

If "KexAlgorithms" does not contain only the algorithms "ecdh-sha2-nistp521,ecdh-sha2-nistp384,ecdh-sha2-nistp256,diffie-hellman-group-exchange-sha256,diffie-hellman-group16-sha512,diffie-hellman-group14-sha256,diffie-hellman-group-exchange-sha256", is commented out, or is missing, this is a finding.

Fix

Configure the SSH daemon to use only FIPS-validated key exchange algorithms by adding or modifying the following line in "/etc/ssh/sshd_config":

KexAlgorithms ecdh-sha2-nistp521,ecdh-sha2-nistp384,ecdh-sha2-nistp256,diffie-hellman-group-exchange-sha256,diffie-hellman-group16-sha512,diffie-hellman-group14-sha256

Restart the "sshd" service for changes to take effect:

$ sudo systemctl restart sshd

Ubuntu 24.04 LTS must configure the SSH client to use FIPS 140-3 approved ciphers to prevent the unauthorized disclosure of information and/or detect changes to information during transmission.

STIG ID: UBTU-24-100850 | SRG: SRG-OS-000250-GPOS-00093 | Severity: medium | CCI: CCI-001453 | Vulnerability Id: V-270670

Vulnerability Discussion

Without cryptographic integrity protections, information can be altered by unauthorized users without detection.

Remote access (e.g., RDP) is access to DOD nonpublic information systems by an authorized user (or an information system) communicating through an external, nonorganization-controlled network. Remote access methods include, for example, dial-up, broadband, and wireless.

Nonlocal maintenance and diagnostic activities are those activities conducted by individuals communicating through a network, either an external network (e.g., the internet) or an internal network.

Local maintenance and diagnostic activities are those activities carried out by individuals physically present at the information system or information system component and not communicating across a network connection.

Encrypting information for transmission protects information from unauthorized disclosure and modification. Cryptographic mechanisms implemented to protect information integrity include, for example, cryptographic hash functions that have common application in digital signatures, checksums, and message authentication codes.

By specifying a cipher list with the order of ciphers being in a "strongest to weakest" orientation, the system will automatically attempt to use the strongest cipher for securing SSH connections.

Check

Verify the SSH client is configured to use only ciphers employing FIPS 140-3 approved algorithms with the following command:

$ sudo grep -r 'Ciphers' /etc/ssh/ssh_config*
Ciphers aes256-gcm@openssh.com,aes128-gcm@openssh.com,aes256-ctr,aes128-ctr

If any ciphers other than "Ciphers aes256-gcm@openssh.com,aes128-gcm@openssh.com,aes256-ctr,aes128-ctr" are listed, the "Ciphers" keyword is missing, or the returned line is commented out, or if multiple conflicting ciphers are returned, this is a finding.

Fix

Configure the Ubuntu 24.04 LTS SSH client to use only ciphers employing FIPS 140-3 approved algorithms by updating the "/etc/ssh/ssh_config" file with the following line:

Ciphers aes256-gcm@openssh.com,aes128-gcm@openssh.com,aes256-ctr,aes128-ctr

Restart the "ssh" service for changes to take effect:

$ sudo systemctl restart ssh

Ubuntu 24.04 LTS SSH client must be configured to use only Message Authentication Codes (MACs) employing FIPS 140-3 validated cryptographic hash algorithms.

STIG ID: UBTU-24-100860 | SRG: SRG-OS-000250-GPOS-00093 | Severity: medium | CCI: CCI-001453 | Vulnerability Id: V-270671

Vulnerability Discussion

Without cryptographic integrity protections, information can be altered by unauthorized users without detection.

Remote access (e.g., RDP) is access to DOD nonpublic information systems by an authorized user (or an information system) communicating through an external, nonorganization-controlled network. Remote access methods include, for example, dial-up, broadband, and wireless. Nonlocal maintenance and diagnostic activities are those activities conducted by individuals communicating through a network, either an external network (e.g., the internet) or an internal network.

Local maintenance and diagnostic activities are those activities carried out by individuals physically present at the information system or information system component and not communicating across a network connection.

Encrypting information for transmission protects information from unauthorized disclosure and modification. Cryptographic mechanisms implemented to protect information integrity include, for example, cryptographic hash functions that have common application in digital signatures, checksums, and message authentication codes.

Check

Verify the SSH client is configured to use only ciphers employing FIPS 140-3 approved algorithms with the following command:

$ sudo grep -ir macs /etc/ssh/ssh_config*
MACs hmac-sha2-512-etm@openssh.com,hmac-sha2-256-etm@openssh.com,hmac-sha2-512,hmac-sha2-256

If any ciphers other than "hmac-sha2-512-etm@openssh.com,hmac-sha2-256-etm@openssh.com,hmac-sha2-512,hmac-sha2-256" are listed, or the returned line is commented out, this is a finding.

Fix

Configure the Ubuntu 24.04 LTS SSH client to use only MACs employing FIPS 140-3 approved algorithms by updating the "/etc/ssh/ssh_config" file with the following line:

MACs hmac-sha2-512-etm@openssh.com,hmac-sha2-256-etm@openssh.com,hmac-sha2-512,hmac-sha2-256

Restart the "ssh" service for changes to take effect:

$ sudo systemctl restart ssh

Ubuntu 24.04 LTS must accept Personal Identity Verification (PIV) credentials.

STIG ID: UBTU-24-100900 | SRG: SRG-OS-000376-GPOS-00161 | Severity: medium | CCI: CCI-001953 | Vulnerability Id: V-270672

Vulnerability Discussion

The use of PIV credentials facilitates standardization and reduces the risk of unauthorized access.

DOD has mandated the use of the common access card (CAC) to support identity management and personal authentication for systems covered under Homeland Security Presidential Directive (HSPD) 12, as well as making the CAC a primary component of layered protection for national security systems.

Check

Verify the "opensc-pcks11" package is installed on the system with the following command:

$ dpkg -l | grep opensc-pkcs11
ii opensc-pkcs11:amd64 0.25.0~rc1-1build2 amd64 Smart card utilities with support for PKCS#15 compatible cards

If the "opensc-pcks11" package is not installed, this is a finding.

Fix

Configure Ubuntu 24.04 LTS to accept PIV credentials.

Install the "opensc-pkcs11" package using the following command:

$ sudo apt install -y opensc-pkcs11

Ubuntu 24.04 LTS must accept Personal Identity Verification (PIV) credentials managed through the Privileged Access Management (PAM) framework.

STIG ID: UBTU-24-100910 | SRG: SRG-OS-000376-GPOS-00161 | Severity: medium | CCI: CCI-001953 | Vulnerability Id: V-270673

Vulnerability Discussion

Check

Verify the "libpam-pcks11" package is installed on the system with the following command:

$ dpkg -l | grep libpam-pkcs11
ii libpam-pkcs11 0.6.12-2build3 amd64 Fully featured PAM module for using PKCS#11 smart cards

If the "libpam-pcks11" package is not installed, this is a finding.

Fix

Configure Ubuntu 24.04 LTS to accept PIV credentials that are managed through the PAM framework.

Install the "libpam-pkcs11" package using the following command:

$ sudo apt install -y libpam-pkcs11

Ubuntu 24.04 LTS must allow users to directly initiate a session lock for all connection types.

STIG ID: UBTU-24-101000 | SRG: SRG-OS-000031-GPOS-00012 | Severity: medium | CCI: CCI-000060,CCI-000057 | Vulnerability Id: V-270674

Vulnerability Discussion

A session lock is a temporary action taken when a user stops work and moves away from the immediate physical vicinity of the information system but does not want to log out because of the temporary nature of the absence.

The session lock is implemented at the point where session activity can be determined. Rather than be forced to wait for a period of time to expire before the user session can be locked, Ubuntu 24.04 LTSs need to provide users with the ability to manually invoke a session lock so users may secure their session if they need to temporarily vacate the immediate physical vicinity.

Satisfies: SRG-OS-000031-GPOS-00012, SRG-OS-000030-GPOS-00011

Check

Verify Ubuntu 24.04 LTS has the "vlock" package installed with the following command:

$ dpkg -l | grep vlock
ii vlock 2.2.2-10 amd64 Virtual Console locking program

If "vlock" is not installed, this is a finding.

Fix

Install the "vlock" package (if it is not already installed) by running the following command:

$ sudo apt install -y vlock

Ubuntu 24.04 LTS when booted must require authentication upon booting into single-user and maintenance modes.

STIG ID: UBTU-24-102000 | SRG: SRG-OS-000080-GPOS-00048 | Severity: high | CCI: CCI-000213 | Vulnerability Id: V-270675

Vulnerability Discussion

To mitigate the risk of unauthorized access to sensitive information by entities that have been issued certificates by DOD-approved PKIs, all DOD systems (e.g., web servers and web portals) must be properly configured to incorporate access control methods that do not rely solely on the possession of a certificate for access.

Successful authentication must not automatically give an entity access to an asset or security boundary. Authorization procedures and controls must be implemented to ensure each authenticated entity also has a validated and current authorization. Authorization is the process of determining whether an entity, once authenticated, is permitted to access a specific asset. Information systems use access control policies and enforcement mechanisms to implement this requirement.

Access control policies include identity-based policies, role-based policies, and attribute-based policies. Access enforcement mechanisms include access control lists, access control matrices, and cryptography. These policies and mechanisms must be employed by the application to control access between users (or processes acting on behalf of users) and objects (e.g., devices, files, records, processes, programs, and domains) in the information system.

Check

Verify Ubuntu 24.04 LTS requires a password for authentication upon booting into single-user and maintenance modes with the following command:

$ sudo grep -i password /boot/grub/grub.cfg
password_pbkdf2 root grub.pbkdf2.sha512.10000.MFU48934NJA87HF8NSD34493GDHF84NG

If the root password entry does not begin with "password_pbkdf2", this is a finding.

Fix

Configure the system to require a password for authentication upon booting into single-user and maintenance modes.

Generate an encrypted (grub) password for root with the following command:

$ grub-mkpasswd-pbkdf2
Enter Password:
Reenter Password:
PBKDF2 hash of your password is grub.pbkdf2.sha512.10000.MFU48934NJD84NF8NSD39993JDHF84NG

Using the hash from the output, modify the "/etc/grub.d/40_custom" file with the following command to add a boot password:

$ sudo sed -i '$i set superusers=\"root\"\npassword_pbkdf2 root <hash>' /etc/grub.d/40_custom

where <hash> is the hash generated by grub-mkpasswd-pbkdf2 command.

Generate an updated "grub.conf" file with the new password by using the following command:

$ sudo update-grub

Ubuntu 24.04 LTS must initiate session audits at system startup.

STIG ID: UBTU-24-102010 | SRG: SRG-OS-000254-GPOS-00095 | Severity: medium | CCI: CCI-001464 | Vulnerability Id: V-270676

Vulnerability Discussion

If auditing is enabled late in the startup process, the actions of some startup processes may not be audited. Some audit systems also maintain state information only available if auditing is enabled before a given process is created.

Check

Verify that Ubuntu 24.04 LTS enables auditing at system startup in grub with the following command

$ sudo grep "^\s*linux" /boot/grub/grub.cfg
linux /vmlinuz-6.8.0-31-generic root=UUID=c92a542f-aee4-4af9-94b2-203624ccb8e3 ro audit=1 quiet splash $vt_handoff
linux /vmlinuz-6.8.0-31-generic root=UUID=c92a542f-aee4-4af9-94b2-203624ccb8e3 ro recovery nomodeset dis_ucode_ldr audit=1

If any linux lines do not contain "audit=1", this is a finding.

Fix

Configure Ubuntu 24.04 LTS to produce audit records at system startup.

Edit the "/etc/default/grub" file and add "audit=1" to the "GRUB_CMDLINE_LINUX" option so that the line looks like this:

GRUB_CMDLINE_LINUX="audit=1"

To update the grub config file, run:

$ sudo update-grub

Ubuntu 24.04 LTS must limit the number of concurrent sessions to 10 for all accounts and/or account types.

STIG ID: UBTU-24-200000 | SRG: SRG-OS-000027-GPOS-00008 | Severity: low | CCI: CCI-000054 | Vulnerability Id: V-270677

Vulnerability Discussion

Ubuntu 24.04 LTS management includes the ability to control the number of users and user sessions that utilize an operating system. Limiting the number of allowed users and sessions per user is helpful in reducing the risks related to denial-of-service (DoS) attacks.

This requirement addresses concurrent sessions for information system accounts and does not address concurrent sessions by single users via multiple system accounts. The maximum number of concurrent sessions must be defined based upon mission needs and the operational environment for each system.

Check

Verify Ubuntu 24.04 LTS limits the number of concurrent sessions to 10 for all accounts and/or account types with the following command:

$ grep maxlogins /etc/security/limits.conf | grep -v '^* hard maxlogins'
* hard maxlogins 10

If the "maxlogins" item does not have a value of "10" or less, is commented out, or is missing, this is a finding.

Fix

Configure Ubuntu 24.04 LTS to limit the number of concurrent sessions to 10 for all accounts and/or account types.

Add the following line to the top of the /etc/security/limits.conf or in a ".conf" file defined in /etc/security/limits.d/:

* hard maxlogins 10

Ubuntu 24.04 LTS must initiate a graphical session lock after 10 minutes of inactivity.

STIG ID: UBTU-24-200020 | SRG: SRG-OS-000029-GPOS-00010 | Severity: medium | CCI: CCI-000057 | Vulnerability Id: V-270678

Vulnerability Discussion

A session lock is a temporary action taken when a user stops work and moves away from the immediate physical vicinity of the information system but does not want to log out because of the temporary nature of the absence.

The session lock is implemented at the point where session activity can be determined.

Regardless of where the session lock is determined and implemented, once invoked, a session lock of Ubuntu 24.04 LTS must remain in place until the user reauthenticates. No other activity aside from reauthentication must unlock the system.

Check

Note: If Ubuntu 24.04 LTS does not have a graphical user interface installed, this requirement is not applicable.

Verify the Ubuntu operation system has a graphical user interface session lock configured to activate after 10 minutes of inactivity with the following commands:

Set the following settings to verify the graphical user interface session is configured to lock the graphical user session after 10 minutes of inactivity:

**$ gsettings get org.gnome.desktop.screensaver lock-enabled
true

$ gsettings get org.gnome.desktop.screensaver lock-delay
uint32 0

$ gsettings get org.gnome.desktop.session idle-delay
uint32 600

Note: If "lock-enabled" is not set to "true", this is a finding.

If "lock-delay" is set to a value greater than "0", or if "idle-delay" is set to a value greater than "600", or either settings are missing, this is a finding.

Fix

Configure Ubuntu 24.04 LTS to lock the current graphical user interface session after 10 minutes of inactivity.

Set the following settings to allow graphical user interface session lock to initiate after 10 minutes of inactivity:

$ gsettings set org.gnome.desktop.screensaver lock-enabled true
$ gsettings set org.gnome.desktop.screensaver lock-delay 0
$ gsettings set org.gnome.desktop.session idle-delay 600

Ubuntu 24.04 LTS must retain a user's session lock until the user reestablishes access using established identification and authentication procedures.

STIG ID: UBTU-24-200040 | SRG: SRG-OS-000028-GPOS-00009 | Severity: medium | CCI: CCI-000056 | Vulnerability Id: V-270679

Vulnerability Discussion

A session lock is a temporary action taken when a user stops work and moves away from the immediate physical vicinity of the information system but does not want to log out because of the temporary nature of the absence.

The session lock is implemented at the point where session activity can be determined.

Regardless of where the session lock is determined and implemented, once invoked, a session lock of Ubuntu 24.04 LTS must remain in place until the user reauthenticates. No other activity aside from reauthentication must unlock the system.

Check

Note: If Ubuntu 24.04 LTS does not have a graphical user interface installed, this requirement is not applicable.

Verify the Ubuntu operation system has a graphical user interface session lock enabled with the following command:

$ sudo gsettings get org.gnome.desktop.screensaver lock-enabled
true

If "lock-enabled" is not set to "true", this is a finding.

Fix

Configure Ubuntu 24.04 LTS to allow a user to lock the current graphical user interface session.

Set the "lock-enabled" setting to allow graphical user interface session locks with the following command:

$ gsettings set org.gnome.desktop.screensaver lock-enabled true

Ubuntu 24.04 LTS must automatically terminate a user session after inactivity timeouts have expired.

STIG ID: UBTU-24-200060 | SRG: SRG-OS-000279-GPOS-00109 | Severity: medium | CCI: CCI-002361 | Vulnerability Id: V-270680

Vulnerability Discussion

Automatic session termination addresses the termination of user-initiated logical sessions in contrast to the termination of network connections associated with communications sessions (i.e., network disconnect). A logical session (for local, network, and remote access) is initiated whenever a user (or process acting on behalf of a user) accesses an organizational information system. Such user sessions can be terminated (and thus terminate user access) without terminating network sessions.

Session termination terminates all processes associated with a user's logical session except those processes specifically created by the user (i.e., session owner) to continue after the session is terminated.

Conditions or trigger events requiring automatic session termination can include, for example, organization-defined periods of user inactivity, targeted responses to certain types of incidents, and time-of-day restrictions on information system use.

This capability is typically reserved for specific operating system functionality where the system owner, data owner, or organization requires additional assurance.

Check

Verify Ubuntu 24.04 LTS automatically terminates a user session after inactivity timeouts have expired with the following command:

$ sudo grep -E "\bTMOUT=[0-9]+" /etc/bash.bashrc /etc/profile.d/*
/etc/profile.d/99-terminal_tmout.sh:TMOUT=600

If "TMOUT" is not set, or if the value is "0" or is commented out, this is a finding.

Fix

Configure Ubuntu 24.04 LTS to automatically terminate a user session after inactivity timeouts have expired or at shutdown.

Create the file "/etc/profile.d/99-terminal_tmout.sh" file if it does not exist.

Modify or append the following line in the "/etc/profile.d/99-terminal_tmout.sh " file:

TMOUT=600

This will set a timeout value of 10 minutes for all future sessions.

To set the timeout for the current sessions, execute the following command over the terminal session:

$ export TMOUT=600

Ubuntu 24.04 LTS must monitor remote access methods.

STIG ID: UBTU-24-200090 | SRG: SRG-OS-000032-GPOS-00013 | Severity: medium | CCI: CCI-000067 | Vulnerability Id: V-270681

Vulnerability Discussion

Remote access services, such as those providing remote access to network devices and information systems, which lack automated monitoring capabilities, increase risk, and make remote user access management difficult at best.

Remote access is access to DOD nonpublic information systems by an authorized user (or an information system) communicating through an external, nonorganization-controlled network. Remote access methods include, for example, dial-up, broadband, and wireless.

Automated monitoring of remote access sessions allows organizations to detect cyberattacks and also ensure ongoing compliance with remote access policies by auditing connection activities of remote access capabilities, such as Remote Desktop Protocol (RDP), on a variety of information system components (e.g., servers, workstations, notebook computers, smartphones, and tablets).

Check

Verify that Ubuntu 24.04 LTS monitors all remote access methods with the following command:

$ grep -E -r '^(auth,authpriv\.\*|daemon\.\*)' /etc/rsyslog.*
/etc/rsyslog.d/50-default.conf:auth,authpriv.* /var/log/auth.log
/etc/rsyslog.d/50-default.conf:daemon.* /var/log/messages

If "auth.*", "authpriv.*", or "daemon.*" are not configured to be logged in at least one of the config files, this is a finding.

Fix

Configure Ubuntu 24.04 LTS to monitor all remote access methods by adding the following lines to the "/etc/rsyslog.d/50-default.conf" file:

auth.*,authpriv.* /var/log/secure
daemon.* /var/log/messages

For the changes to take effect, restart the "rsyslog" service with the following command:

$ sudo systemctl restart rsyslog.service

Ubuntu 24.04 LTS must automatically remove or disable emergency accounts after 72 hours.

STIG ID: UBTU-24-200250 | SRG: SRG-OS-000002-GPOS-00002 | Severity: medium | CCI: CCI-000016,CCI-001682 | Vulnerability Id: V-270682

Vulnerability Discussion

Temporary accounts are privileged or nonprivileged accounts established during pressing circumstances, such as new software or hardware configuration or an incident response, where the need for prompt account activation requires bypassing normal account authorization procedures. If any inactive temporary accounts are left enabled on the system and are not either manually removed or automatically expired within 72 hours, the security posture of the system will be degraded and exposed to exploitation by unauthorized users or insider threat actors.

Temporary accounts are different from emergency accounts. Emergency accounts, also known as "last resort" or "break glass" accounts, are local logon accounts enabled on the system for emergency use by authorized system administrators to manage a system when standard logon methods are failing or not available. Emergency accounts are not subject to manual removal or scheduled expiration requirements.

The automatic expiration of temporary accounts may be extended as needed by the circumstances but it must not be extended indefinitely. A documented permanent account must be established for privileged users who need long-term maintenance accounts.

Satisfies: SRG-OS-000002-GPOS-00002, SRG-OS-000123-GPOS-00064

Check

Verify temporary accounts have been provisioned with an expiration date of 72 hours with the following command:

$ sudo chage -l <temporary_account_name> | grep -i "account expires"

Verify each of these accounts has an expiration date set within 72 hours.

If any temporary accounts have no expiration date set or do not expire within 72 hours, this is a finding.

Fix

Configure Ubuntu 24.04 LTS to expire temporary accounts after 72 hours with the following command:

$ sudo chage -E $(date -d +3days +%Y-%m-%d) <temporary_account_name>

Ubuntu 24.04 LTS must disable account identifiers (individuals, groups, roles, and devices) after 35 days of inactivity.

STIG ID: UBTU-24-200260 | SRG: SRG-OS-000118-GPOS-00060 | Severity: medium | CCI: CCI-003627,CCI-003628 | Vulnerability Id: V-270683

Vulnerability Discussion

Inactive identifiers pose a risk to systems and applications because attackers may exploit an inactive identifier and potentially obtain undetected access to the system. Owners of inactive accounts will not notice if unauthorized access to their user account has been obtained.

Operating systems need to track periods of inactivity and disable application identifiers after 35 days of inactivity.

Satisfies: SRG-OS-000118-GPOS-00060, SRG-OS-000590-GPOS-00110

Check

Verify the account identifiers (individuals, groups, roles, and devices) are disabled after 35 days of inactivity with the following command:

Check the account inactivity value by performing the following command:

$ grep INACTIVE /etc/default/useradd
INACTIVE=35

If "INACTIVE" is not set to a value 0<[VALUE]<=35, is commented out, or is missing, this is a finding.

Fix

Configure Ubuntu 24.04 LTS to disable account identifiers after 35 days of inactivity after the password expiration.

Run the following command to change the configuration for adduser:

$ sudo useradd -D -f 35

Note: DOD recommendation is 35 days, but a lower value is acceptable. The value "0" will disable the account immediately after the password expires.

Ubuntu 24.04 LTS must generate audit records for all account creations, modifications, disabling, and termination events that affect /etc/passwd.

STIG ID: UBTU-24-200280 | SRG: SRG-OS-000004-GPOS-00004 | Severity: medium | CCI: CCI-000018,CCI-001403,CCI-001404,CCI-001405,CCI-002130,CCI-000172 | Vulnerability Id: V-270684

Vulnerability Discussion

Once an attacker establishes access to a system, the attacker often attempts to create a persistent method of reestablishing access. One way to accomplish this is for the attacker to create an account. Auditing account creation actions provides logging that can be used for forensic purposes.

To address access requirements, many operating systems may be integrated with enterprise-level authentication/access/auditing mechanisms that meet or exceed access control policy requirements.

Satisfies: SRG-OS-000004-GPOS-00004, SRG-OS-000239-GPOS-00089, SRG-OS-000240-GPOS-00090, SRG-OS-000241-GPOS-00091, SRG-OS-000303-GPOS-00120, SRG-OS-000458-GPOS-00203, SRG-OS-000463-GPOS-00207, SRG-OS-000476-GPOS-00221

Check

Verify Ubuntu 24.04 LTS generates audit records for all account creations, modifications, disabling, and termination events that affect "/etc/passwd" with the following command:

$ sudo auditctl -l | grep passwd
-w /etc/passwd -p wa -k usergroup_modification

If the command does not return a line that matches the example or the line is commented out, this is a finding.

Note: The "-k" allows for specifying an arbitrary identifier, and the string after it does not need to match the example output above.

Fix

Configure Ubuntu 24.04 LTS to generate audit records for all account creations, modifications, disabling, and termination events that affect "/etc/passwd".

Add or update the following rule to "/etc/audit/rules.d/stig.rules":

-w /etc/passwd -p wa -k usergroup_modification

To reload the rules file, issue the following command:

$ sudo augenrules --load

Ubuntu 24.04 LTS must generate audit records for all account creations, modifications, disabling, and termination events that affect /etc/group.

STIG ID: UBTU-24-200290 | SRG: SRG-OS-000004-GPOS-00004 | Severity: medium | CCI: CCI-000018,CCI-001403,CCI-001404,CCI-001405,CCI-002130,CCI-000172 | Vulnerability Id: V-270685

Vulnerability Discussion

Check

Verify Ubuntu 24.04 LTS generates audit records for all account creations, modifications, disabling, and termination events that affect "/etc/group" with the following command:

$ sudo auditctl -l | grep group
-w /etc/group -p wa -k usergroup_modification

If the command does not return a line that matches the example or the line is commented out, this is a finding.

Note: The "-k" allows for specifying an arbitrary identifier, and the string after it does not need to match the example output above.

Fix

Configure Ubuntu 24.04 LTS to generate audit records for all account creations, modifications, disabling, and termination events that affect "/etc/group".

Add or update the following rule to "/etc/audit/rules.d/stig.rules":

-w /etc/group -p wa -k usergroup_modification

To reload the rules file, issue the following command:

$ sudo augenrules --load

Ubuntu 24.04 LTS must generate audit records for all account creations, modifications, disabling, and termination events that affect /etc/shadow.

STIG ID: UBTU-24-200300 | SRG: SRG-OS-000004-GPOS-00004 | Severity: medium | CCI: CCI-000018,CCI-001403,CCI-001404,CCI-001405,CCI-002130,CCI-000172 | Vulnerability Id: V-270686

Vulnerability Discussion

Check

Verify Ubuntu 24.04 LTS generates audit records for all account creations, modifications, disabling, and termination events that affect "/etc/shadow" with the following command:

$ sudo auditctl -l | grep shadow
-w /etc/shadow -p wa -k usergroup_modification

If the command does not return a line that matches the example or the line is commented out, this is a finding.

Note: The "-k" allows for specifying an arbitrary identifier, and the string after it does not need to match the example output above.

Fix

Configure Ubuntu 24.04 LTS to generate audit records for all account creations, modifications, disabling, and termination events that affect "/etc/shadow".

Add or update the following rule to "/etc/audit/rules.d/stig.rules":

-w /etc/shadow -p wa -k usergroup_modification

To reload the rules file, issue the following command:

$ sudo augenrules --load

Ubuntu 24.04 LTS must generate audit records for all account creations, modifications, disabling, and termination events that affect /etc/gshadow.

STIG ID: UBTU-24-200310 | SRG: SRG-OS-000004-GPOS-00004 | Severity: medium | CCI: CCI-000018,CCI-001403,CCI-001404,CCI-001405,CCI-002130,CCI-000172 | Vulnerability Id: V-270687

Vulnerability Discussion

Check

Verify Ubuntu 24.04 LTS generates audit records for all account creations, modifications, disabling, and termination events that affect "/etc/gshadow" with the following command:

$ sudo auditctl -l | grep gshadow
-w /etc/gshadow -p wa -k usergroup_modification

If the command does not return a line that matches the example or the line is commented out, this is a finding.

Note: The "-k" allows for specifying an arbitrary identifier, and the string after it does not need to match the example output above.

Fix

Configure Ubuntu 24.04 LTS to generate audit records for all account creations, modifications, disabling, and termination events that affect "/etc/gshadow".

Add or update the following rule to "/etc/audit/rules.d/stig.rules":

-w /etc/gshadow -p wa -k usergroup_modification

To reload the rules file, issue the following command:

$ sudo augenrules --load

Ubuntu 24.04 LTS must generate audit records for all account creations, modifications, disabling, and termination events that affect /etc/opasswd.

STIG ID: UBTU-24-200320 | SRG: SRG-OS-000004-GPOS-00004 | Severity: medium | CCI: CCI-000018,CCI-001403,CCI-001404,CCI-001405,CCI-002130,CCI-000172 | Vulnerability Id: V-270688

Vulnerability Discussion

Check

Verify Ubuntu 24.04 LTS generates audit records for all account creations, modifications, disabling, and termination events that affect "/etc/security/opasswd" with the following command:

$ sudo auditctl -l | grep opasswd
-w /etc/security/opasswd -p wa -k usergroup_modification

If the command does not return a line that matches the example or the line is commented out, this is a finding.

Note: The "-k" allows for specifying an arbitrary identifier, and the string after it does not need to match the example output above.

Fix

Configure Ubuntu 24.04 LTS to generate audit records for all account creations, modifications, disabling, and termination events that affect "/etc/security/opasswd".

Add or update the following rule to "/etc/audit/rules.d/stig.rules":

-w /etc/security/opasswd -p wa -k usergroup_modification

To reload the rules file, issue the following command:

$ sudo augenrules --load

Ubuntu 24.04 LTS must prevent all software from executing at higher privilege levels than users executing the software and the audit system must be configured to audit the execution of privileged functions.

STIG ID: UBTU-24-200580 | SRG: SRG-OS-000326-GPOS-00126 | Severity: medium | CCI: CCI-002233,CCI-002234,CCI-004188 | Vulnerability Id: V-270689

Vulnerability Discussion

In certain situations, software applications/programs need to execute with elevated privileges to perform required functions. However, if the privileges required for execution are at a higher level than the privileges assigned to organizational users invoking such applications/programs, those users are indirectly provided with greater privileges than assigned by the organizations.

Some programs and processes are required to operate at a higher privilege level and therefore, must be excluded from the organization-defined software list after review.

Satisfies: SRG-OS-000326-GPOS-00126, SRG-OS-000327-GPOS-00127, SRG-OS-000755-GPOS-00220

Check

Verify Ubuntu 24.04 LTS audits the execution of privilege functions by auditing the "execve" system call with the following command:

$ sudo auditctl -l | grep execve
-a always,exit -F arch=b64 -S execve -C uid!=euid -F euid=0 -F key=execpriv
-a always,exit -F arch=b64 -S execve -C gid!=egid -F egid=0 -F key=execpriv
-a always,exit -F arch=b32 -S execve -C uid!=euid -F euid=0 -F key=execpriv
-a always,exit -F arch=b32 -S execve -C gid!=egid -F egid=0 -F key=execpriv

If the command does not return lines that match the example or the lines are commented out, this is a finding.

Notes:
- For 32-bit architectures, only the 32-bit specific output lines from the commands are required.
- The "-k" allows for specifying an arbitrary identifier, and the string after it does not need to match the example output above.

Fix

Configure Ubuntu 24.04 LTS to audit the execution of all privileged functions.

Add or update the following rules in the "/etc/audit/rules.d/stig.rules" file:

-a always,exit -F arch=b64 -S execve -C uid!=euid -F euid=0 -F key=execpriv
-a always,exit -F arch=b64 -S execve -C gid!=egid -F egid=0 -F key=execpriv
-a always,exit -F arch=b32 -S execve -C uid!=euid -F euid=0 -F key=execpriv
-a always,exit -F arch=b32 -S execve -C gid!=egid -F egid=0 -F key=execpriv

Notes: For 32-bit architectures, only the 32-bit specific entries are required.

To reload the rules file, issue the following command:

$ sudo augenrules --load

Ubuntu 24.04 LTS must automatically lock an account until the locked account is released by an administrator when three unsuccessful logon attempts have been made.

STIG ID: UBTU-24-200610 | SRG: SRG-OS-000021-GPOS-00005 | Severity: low | CCI: CCI-000044,CCI-002238 | Vulnerability Id: V-270690

Vulnerability Discussion

By limiting the number of failed logon attempts, the risk of unauthorized system access via user password guessing, otherwise known as brute-forcing, is reduced. Limits are imposed by locking the account.

Satisfies: SRG-OS-000021-GPOS-00005, SRG-OS-000329-GPOS-00128

Check

Verify that Ubuntu 24.04 LTS utilizes the "pam_faillock" module with the following command:

$ grep faillock /etc/pam.d/common-auth
auth [default=die] pam_faillock.so authfail
auth sufficient pam_faillock.so authsucc

If the pam_faillock.so module is not present in the "/etc/pam.d/common-auth" file, this is a finding.

Verify the pam_faillock module is configured to use the following options:

$ sudo egrep 'silent|audit|deny|fail_interval| unlock_time' /etc/security/faillock.conf
audit
silent
deny = 3
fail_interval = 900
unlock_time = 0

If the "silent" keyword is missing or commented out, this is a finding.
If the "audit" keyword is missing or commented out, this is a finding.
If the "deny" keyword is missing, commented out, or set to a value greater than "3", this is a finding.
If the "fail_interval" keyword is missing, commented out, or set to a value greater than "900", this is a finding.
If the "unlock_time" keyword is missing, commented out, or not set to "0", this is a finding.

Fix

Configure Ubuntu 24.04 LTS to utilize the "pam_faillock" module.

Edit the /etc/pam.d/common-auth file to add the following lines below the "auth" definition for pam_unix.so:
auth [default=die] pam_faillock.so authfail
auth sufficient pam_faillock.so authsucc

Configure the "pam_faillock" module to use the following options:

Edit the /etc/security/faillock.conf file and add/update the following keywords and values:
audit
silent
deny = 3
fail_interval = 900
unlock_time = 0

Ubuntu 24.04 LTS must display the Standard Mandatory DOD Notice and Consent Banner before granting access to via an SSH logon.

STIG ID: UBTU-24-200640 | SRG: SRG-OS-000023-GPOS-00006 | Severity: medium | CCI: CCI-000048,CCI-001384,CCI-001385,CCI-001386,CCI-001387,CCI-001388 | Vulnerability Id: V-270691

Vulnerability Discussion

Display of a standardized and approved use notification before granting access to the publicly accessible operating system ensures privacy and security notification verbiage used is consistent with applicable federal laws, Executive Orders, directives, policies, regulations, standards, and guidance.

System use notifications are required only for access via logon interfaces with human users and are not required when such human interfaces do not exist.

The banner must be formatted in accordance with applicable DOD policy. Use the following verbiage for operating systems that can accommodate banners of 1300 characters:

"You are accessing a U.S. Government (USG) Information System (IS) that is provided for USG-authorized use only.

By using this IS (which includes any device attached to this IS), you consent to the following conditions:

-The USG routinely intercepts and monitors communications on this IS for purposes including, but not limited to, penetration testing, COMSEC monitoring, network operations and defense, personnel misconduct (PM), law enforcement (LE), and counterintelligence (CI) investigations.

-At any time, the USG may inspect and seize data stored on this IS.

-Communications using, or data stored on, this IS are not private, are subject to routine monitoring, interception, and search, and may be disclosed or used for any USG-authorized purpose.

-This IS includes security measures (e.g., authentication and access controls) to protect USG interests--not for your personal benefit or privacy.

-Notwithstanding the above, using this IS does not constitute consent to PM, LE or CI investigative searching or monitoring of the content of privileged communications, or work product, related to personal representation or services by attorneys, psychotherapists, or clergy, and their assistants. Such communications and work product are private and confidential. See User Agreement for details."

Use the following verbiage for operating systems that have severe limitations on the number of characters that can be displayed in the banner:

"I've read (literal ampersand) consent to terms in IS user agreem't."

Satisfies: SRG-OS-000023-GPOS-00006, SRG-OS-000228-GPOS-00088

Check

Verify Ubuntu 24.04 LTS displays the Standard Mandatory DOD Notice and Consent Banner before granting access via an SSH logon with the following command:

$ sudo grep -ir banner /etc/ssh/sshd_config*
/etc/ssh/sshd_config:Banner /etc/issue.net

The command will return the banner option along with the name of the file that contains the SSH banner. If the line is commented out, missing, or conflicting results are returned, this is a finding.

Verify the specified banner file matches the Standard Mandatory DOD Notice and Consent Banner exactly:

$ cat /etc/issue.net
"You are accessing a U.S. Government (USG) Information System (IS) that is provided for USG-authorized use only.

By using this IS (which includes any device attached to this IS), you consent to the following conditions:

-The USG routinely intercepts and monitors communications on this IS for purposes including, but not limited to, penetration testing, COMSEC monitoring, network operations and defense, personnel misconduct (PM), law enforcement (LE), and counterintelligence (CI) investigations.

-At any time, the USG may inspect and seize data stored on this IS.

-Communications using, or data stored on, this IS are not private, are subject to routine monitoring, interception, and search, and may be disclosed or used for any USG-authorized purpose.

-This IS includes security measures (e.g., authentication and access controls) to protect USG interests--not for your personal benefit or privacy.

-Notwithstanding the above, using this IS does not constitute consent to PM, LE or CI investigative searching or monitoring of the content of privileged communications, or work product, related to personal representation or services by attorneys, psychotherapists, or clergy, and their assistants. Such communications and work product are private and confidential. See User Agreement for details."

If the banner text does not match the Standard Mandatory DOD Notice and Consent Banner exactly, this is a finding.

Fix

Configure Ubuntu 24.04 LTS to display the Standard Mandatory DOD Notice and Consent Banner before granting access via an SSH logon.

Set the parameter Banner in "/etc/ssh/sshd_config" to point to the "/etc/issue.net" file:

$ sudo sed -i '/^Banner/d' /etc/ssh/sshd_config
$ sudo sed -i '$aBanner /etc/issue.net' /etc/ssh/sshd_config

Either create the file containing the banner or replace the text in the file with the Standard Mandatory DOD Notice and Consent Banner. The DOD required text is:

"You are accessing a U.S. Government (USG) Information System (IS) that is provided for USG-authorized use only.

By using this IS (which includes any device attached to this IS), you consent to the following conditions:

-The USG routinely intercepts and monitors communications on this IS for purposes including, but not limited to, penetration testing, COMSEC monitoring, network operations and defense, personnel misconduct (PM), law enforcement (LE), and counterintelligence (CI) investigations.

-At any time, the USG may inspect and seize data stored on this IS.

-Communications using, or data stored on, this IS are not private, are subject to routine monitoring, interception, and search, and may be disclosed or used for any USG-authorized purpose.

-This IS includes security measures (e.g., authentication and access controls) to protect USG interests--not for your personal benefit or privacy.

-Notwithstanding the above, using this IS does not constitute consent to PM, LE or CI investigative searching or monitoring of the content of privileged communications, or work product, related to personal representation or services by attorneys, psychotherapists, or clergy, and their assistants. Such communications and work product are private and confidential. See User Agreement for details."

Restart the SSH daemon for the changes to take effect and then signal the SSH server to reload the configuration file:

$ sudo systemctl -s SIGHUP kill sshd

Ubuntu 24.04 LTS must enable the graphical user logon banner to display the Standard Mandatory DOD Notice and Consent Banner before granting local access to the system via a graphical user logon.

STIG ID: UBTU-24-200650 | SRG: SRG-OS-000023-GPOS-00006 | Severity: medium | CCI: CCI-000048 | Vulnerability Id: V-270692

Vulnerability Discussion

Display of a standardized and approved use notification before granting access to Ubuntu 24.04 LTS ensures privacy and security notification verbiage used is consistent with applicable federal laws, Executive Orders, directives, policies, regulations, standards, and guidance.

System use notifications are required only for access via logon interfaces with human users and are not required when such human interfaces do not exist.

The banner must be formatted in accordance with applicable DOD policy. Use the following verbiage for operating systems that can accommodate banners of 1300 characters:

"You are accessing a U.S. Government (USG) Information System (IS) that is provided for USG-authorized use only.

By using this IS (which includes any device attached to this IS), you consent to the following conditions:

-The USG routinely intercepts and monitors communications on this IS for purposes including, but not limited to, penetration testing, COMSEC monitoring, network operations and defense, personnel misconduct (PM), law enforcement (LE), and counterintelligence (CI) investigations.

-At any time, the USG may inspect and seize data stored on this IS.

-Communications using, or data stored on, this IS are not private, are subject to routine monitoring, interception, and search, and may be disclosed or used for any USG-authorized purpose.

-This IS includes security measures (e.g., authentication and access controls) to protect USG interests--not for your personal benefit or privacy.

-Notwithstanding the above, using this IS does not constitute consent to PM, LE or CI investigative searching or monitoring of the content of privileged communications, or work product, related to personal representation or services by attorneys, psychotherapists, or clergy, and their assistants. Such communications and work product are private and confidential. See User Agreement for details."

Use the following verbiage for operating systems that have severe limitations on the number of characters that can be displayed in the banner:

"I've read (literal ampersand) consent to terms in IS user agreem't."

Check

Note: If the system does not have a graphical user interface installed, this requirement is not applicable.

Verify Ubuntu 24.04 LTS is configured to display the Standard Mandatory DOD Notice and Consent Banner before granting access to Ubuntu 24.04 LTS via a graphical user logon with the following command:

$ grep ^banner-message-enable /etc/gdm3/greeter.dconf-defaults
banner-message-enable=true

If the value for "banner-message-enable" is set to "false", the line is commented out, or no value is returned, this is a finding.

Fix

Configure Ubuntu 24.04 LTS to display the Standard Mandatory DOD Notice and Consent Banner before granting access to Ubuntu 24.04 LTS via a graphical user logon.

Edit the "/etc/gdm3/greeter.dconf-defaults" file.

Look for the "banner-message-enable" parameter under the "[org/gnome/login-screen]" section and uncomment it (remove the leading "#" characters):
[org/gnome/login-screen]
banner-message-enable=true

Update the GDM with the new configuration:

$ sudo dconf update
$ sudo systemctl restart gdm3

Ubuntu 24.04 LTS must display the Standard Mandatory DOD Notice and Consent Banner before granting local access to the system via a graphical user logon.

STIG ID: UBTU-24-200660 | SRG: SRG-OS-000023-GPOS-00006 | Severity: medium | CCI: CCI-000048 | Vulnerability Id: V-270693

Vulnerability Discussion

Check

Note: If the system does not have a graphical user interface installed, this requirement is not applicable.

Verify Ubuntu 24.04 LTS displays the Standard Mandatory DOD Notice and Consent Banner before granting access to Ubuntu 24.04 LTS via a graphical user logon with the command:

$ grep ^banner-message-text /etc/gdm3/greeter.dconf-defaults
banner-message-text="You are accessing a U.S. Government $USG$ Information System $IS$ that is provided for USG-authorized use only.\s+By using this IS $which includes any device attached to this IS$, you consent to the following conditions:\s+-The USG routinely intercepts and monitors communications on this IS for purposes including, but not limited to, penetration testing, COMSEC monitoring, network operations and defense, personnel misconduct $PM$, law enforcement $LE$, and counterintelligence $CI$ investigations.\s+-At any time, the USG may inspect and seize data stored on this IS.\s+-Communications using, or data stored on, this IS are not private, are subject to routine monitoring, interception, and search, and may be disclosed or used for any USG-authorized purpose.\s+-This IS includes security measures $e.g., authentication and access controls$ to protect USG interests--not for your personal benefit or privacy.\s+-Notwithstanding the above, using this IS does not constitute consent to PM, LE or CI investigative searching or monitoring of the content of privileged communications, or work product, related to personal representation or services by attorneys, psychotherapists, or clergy, and their assistants. Such communications and work product are private and confidential. See User Agreement for details."

If the banner-message-text is missing, commented out, or does not match the Standard Mandatory DOD Notice and Consent Banner exactly, this is a finding.

Fix

Configure Ubuntu 24.04 LTS displays the Standard Mandatory DOD Notice and Consent Banner before granting access to Ubuntu 24.04 LTS via a graphical user logon.

Edit the "/etc/gdm3/greeter.dconf-defaults" file.

Set the "banner-message-text" line to contain the appropriate banner message text as shown below:

banner-message-text='You are accessing a U.S. Government (USG) Information System (IS) that is provided for USG-authorized use only.\n\nBy using this IS (which includes any device attached to this IS), you consent to the following conditions:\n\n-The USG routinely intercepts and monitors communications on this IS for purposes including, but not limited to, penetration testing, COMSEC monitoring, network operations and defense, personnel misconduct (PM), law enforcement (LE), and counterintelligence (CI) investigations.\n\n-At any time, the USG may inspect and seize data stored on this IS.\n\n-Communications using, or data stored on, this IS are not private, are subject to routine monitoring, interception, and search, and may be disclosed or used for any USG-authorized purpose.\n\n-This IS includes security measures (e.g., authentication and access controls) to protect USG interests--not for your personal benefit or privacy.\n\n-Notwithstanding the above, using this IS does not constitute consent to PM, LE or CI investigative searching or monitoring of the content of privileged communications, or work product, related to personal representation or services by attorneys, psychotherapists, or clergy, and their assistants. Such communications and work product are private and confidential. See User Agreement for details.'

Update the GDM with the new configuration:

$ sudo dconf update
$ sudo systemctl restart gdm3

Ubuntu 24.04 LTS must be configured to enforce the acknowledgement of the Standard Mandatory DOD Notice and Consent Banner for all SSH connections.

STIG ID: UBTU-24-200680 | SRG: SRG-OS-000024-GPOS-00007 | Severity: medium | CCI: CCI-000050 | Vulnerability Id: V-270694

Vulnerability Discussion

The banner must be acknowledged by the user prior to allowing the user access to Ubuntu 24.04 LTS. This provides assurance that the user has seen the message and accepted the conditions for access. If the consent banner is not acknowledged by the user, DOD will not be in compliance with system use notifications required by law.

Ubuntu 24.04 LTS must prevent further activity until the user executes a positive action to manifest agreement.

Check

Verify Ubuntu 24.04 LTS is configured to prompt a user to acknowledge the Standard Mandatory DOD Notice and Consent Banner before granting access with the following command:

$ less /etc/profile.d/ssh_confirm.sh
#!/bin/bash

if [ -n "$SSH_CLIENT" ] || [ -n "$SSH_TTY" ]; then
while true; do
read -p "

You are accessing a U.S. Government (USG) Information System (IS) that is provided for USG-authorized use only.

By using this IS (which includes any device attached to this IS), you consent to the following conditions:

-The USG routinely intercepts and monitors communications on this IS for purposes including, but not limited to, penetration testing, COMSEC monitoring, network operations and defense, personnel misconduct (PM), law enforcement (LE), and counterintelligence (CI) investigations.

-At any time, the USG may inspect and seize data stored on this IS.

-Communications using, or data stored on, this IS are not private, are subject to routine monitoring, interception, and search, and may be disclosed or used for any USG-authorized purpose.

-This IS includes security measures (e.g., authentication and access controls) to protect USG interests--not for your personal benefit or privacy.

-Notwithstanding the above, using this IS does not constitute consent to PM, LE or CI investigative searching or monitoring of the content of privileged communications, or work product, related to personal representation or services by attorneys, psychotherapists, or clergy, and their assistants. Such communications and work product are private and confidential. See User Agreement for details.

Do you agree? [y/N] " yn
case $yn in
[Yy]* ) break ;;
[Nn]* ) exit 1 ;;
esac
done
fi

If the output does not match the text above, this is a finding.

Fix

Configure Ubuntu 24.04 LTS to prompt a user to acknowledge the Standard Mandatory DOD Notice and Consent Banner before granting access:

$ sudo vi /etc/profile.d/ssh_confirm.sh
#!/bin/bash

if [ -n "$SSH_CLIENT" ] || [ -n "$SSH_TTY" ]; then
while true; do
read -p "

You are accessing a U.S. Government (USG) Information System (IS) that is provided for USG-authorized use only.

By using this IS (which includes any device attached to this IS), you consent to the following conditions:

-The USG routinely intercepts and monitors communications on this IS for purposes including, but not limited to, penetration testing, COMSEC monitoring, network operations and defense, personnel misconduct (PM), law enforcement (LE), and counterintelligence (CI) investigations.

-At any time, the USG may inspect and seize data stored on this IS.

-Communications using, or data stored on, this IS are not private, are subject to routine monitoring, interception, and search, and may be disclosed or used for any USG-authorized purpose.

-This IS includes security measures (e.g., authentication and access controls) to protect USG interests--not for your personal benefit or privacy.

-Notwithstanding the above, using this IS does not constitute consent to PM, LE or CI investigative searching or monitoring of the content of privileged communications, or work product, related to personal representation or services by attorneys, psychotherapists, or clergy, and their assistants. Such communications and work product are private and confidential. See User Agreement for details.

Do you agree? [y/N] " yn
case $yn in
[Yy]* ) break ;;
[Nn]* ) exit 1 ;;
esac
done
fi

Note: The "ssh_confirm.sh" script is provided as a supplemental file to this document.

Ubuntu 24.04 LTS Advance Package Tool (APT) must be configured to prevent the installation of patches, service packs, device drivers, or Ubuntu 24.04 LTS components without verification they have been digitally signed using a certificate that is recognized and approved by the organization.

STIG ID: UBTU-24-300001 | SRG: SRG-OS-000366-GPOS-00153 | Severity: low | CCI: CCI-003992 | Vulnerability Id: V-270695

Vulnerability Discussion

Changes to any software components can have significant effects on the overall security of Ubuntu 24.04 LTS. This requirement ensures the software has not been tampered with and that it has been provided by a trusted vendor.

Accordingly, patches, service packs, device drivers, or operating system components must be signed with a certificate recognized and approved by the organization.

Verifying the authenticity of the software prior to installation validates the integrity of the patch or upgrade received from a vendor. This ensures the software has not been tampered with and that it has been provided by a trusted vendor. Self-signed certificates are disallowed by this requirement. Ubuntu 24.04 LTS will not have to verify the software again. This requirement does not mandate DOD certificates for this purpose; however, the certificate used to verify the software must be from an approved CA.

Check

Verify that APT is configured to prevent the installation of patches, service packs, device drivers, or Ubuntu 24.04 LTS components without verification they have been digitally signed using a certificate recognized and approved by the organization with the following command:

$ grep AllowUnauthenticated /etc/apt/apt.conf.d/*

If any files are returned from the command with "AllowUnauthenticated" are set to "true", this is a finding.

Fix

Configure APT to prevent the installation of patches, service packs, device drivers, or Ubuntu 24.04 LTS components without verification they have been digitally signed using a certificate recognized and approved by the organization.

Remove/update any APT configuration files that contain the variable "AllowUnauthenticated" to "false" or remove "AllowUnauthenticated" entirely from each file. Below is an example of setting the "AllowUnauthenticated" variable to "false":

APT::Get::AllowUnauthenticated "false";

Ubuntu 24.04 LTS library files must have mode 0755 or less permissive.

STIG ID: UBTU-24-300006 | SRG: SRG-OS-000259-GPOS-00100 | Severity: medium | CCI: CCI-001499 | Vulnerability Id: V-270696

Vulnerability Discussion

If Ubuntu 24.04 LTS were to allow any user to make changes to software libraries, then those changes might be implemented without undergoing the appropriate testing and approvals that are part of a robust change management process.

This requirement applies to operating systems with software libraries that are accessible and configurable, as in the case of interpreted languages. Software libraries also include privileged programs that execute with escalated privileges. Only qualified and authorized individuals must be allowed to obtain access to information system components for purposes of initiating changes, including upgrades and modifications.

Check

Verify the systemwide shared library files contained in the directories "/lib", "/lib64", and "/usr/lib" have mode 0755 or less permissive with the following command:

$ sudo find /lib /lib64 /usr/lib -perm /022 -type f -exec stat -c "%n %a" '{}' \;

If any files are found to be group-writable or world-writable, this is a finding.

Fix

Configure the library files to be protected from unauthorized access. Run the following command:

$ sudo find /lib /lib64 /usr/lib -perm /022 -type f -exec chmod 755 '{}' \;

Ubuntu 24.04 LTS library files must be owned by root.

STIG ID: UBTU-24-300007 | SRG: SRG-OS-000259-GPOS-00100 | Severity: medium | CCI: CCI-001499 | Vulnerability Id: V-270697

Vulnerability Discussion

Check

Verify the systemwide shared library files contained in the directories "/lib", "/lib64", and "/usr/lib" are owned by root with the following command:

$ sudo find /lib /usr/lib /lib64 ! -user root -type f -exec stat -c "%n %U" '{}' \;

If any systemwide library file is returned, this is a finding.

Fix

Configure the system library files to be protected from unauthorized access. Run the following command:

$ sudo find /lib /usr/lib /lib64 ! -user root -type f -exec chown root '{}' \;

Ubuntu 24.04 LTS library directories must be owned by root.

STIG ID: UBTU-24-300008 | SRG: SRG-OS-000259-GPOS-00100 | Severity: medium | CCI: CCI-001499 | Vulnerability Id: V-270698

Vulnerability Discussion

Check

Verify the systemwide shared library directories "/lib", "/lib64", and "/usr/lib" are owned by root with the following command:

$ sudo find /lib /usr/lib /lib64 ! -user root -type d -exec stat -c "%n %U" '{}' \;

If any systemwide library directory is returned, this is a finding.

Fix

Configure the library files and their respective parent directories to be protected from unauthorized access. Run the following command:

$ sudo find /lib /usr/lib /lib64 ! -user root -type d -exec chown root '{}' \;

Ubuntu 24.04 LTS library files must be group-owned by root or a system account.

STIG ID: UBTU-24-300009 | SRG: SRG-OS-000259-GPOS-00100 | Severity: medium | CCI: CCI-001499 | Vulnerability Id: V-270699

Vulnerability Discussion

Check

Verify the systemwide library files contained in the directories "/lib", "/lib64", and "/usr/lib" are group-owned by root, or a required system account, with the following command:

$ sudo find /lib /usr/lib /lib64 ! -group root -type f -exec stat -c "%n %G" '{}' \;

If any systemwide shared library file is returned and is not group-owned by a required system account, this is a finding.

Fix

Configure the system library files to be protected from unauthorized access. Run the following command, replacing "[FILE]" with any system command file not group-owned by "root" or a required system account:

$ sudo chgrp root [FILE]

Ubuntu 24.04 LTS library directories must be group-owned by root.

STIG ID: UBTU-24-300010 | SRG: SRG-OS-000259-GPOS-00100 | Severity: medium | CCI: CCI-001499 | Vulnerability Id: V-270700

Vulnerability Discussion

Check

Verify the systemwide library directories "/lib", "/lib64", and "/usr/lib" are group-owned by root with the following command:

$ sudo find /lib /usr/lib /lib64 ! -group root -type d -exec stat -c "%n %G" '{}' \;

If any systemwide shared library directory is returned, this is a finding.

Fix

Configure the system library directories to be protected from unauthorized access. Run the following command:

$ sudo find /lib /usr/lib /lib64 ! -group root -type d -exec chgrp root '{}' \;

Ubuntu 24.04 LTS must have system commands set to a mode of 0755 or less permissive.

STIG ID: UBTU-24-300011 | SRG: SRG-OS-000259-GPOS-00100 | Severity: medium | CCI: CCI-001499 | Vulnerability Id: V-270701

Vulnerability Discussion

If Ubuntu 24.04 LTS were to allow any user to make changes to software libraries, then those changes might be implemented without undergoing the appropriate testing and approvals that are part of a robust change management process.

This requirement applies to Ubuntu 24.04 LTS with software libraries that are accessible and configurable, as in the case of interpreted languages. Software libraries also include privileged programs that execute with escalated privileges. Only qualified and authorized individuals must be allowed to obtain access to information system components for purposes of initiating changes, including upgrades and modifications.

Check

Verify the system commands contained in the following directories have mode 0755 or less permissive with the following command:

$ sudo find /bin /sbin /usr/bin /usr/sbin /usr/local/bin /usr/local/sbin -perm /022 -type f -exec stat -c "%n %a" '{}' \;

If any files are found to be group-writable or world-writable, this is a finding.

Fix

Configure the system commands to be protected from unauthorized access. Run the following command:

$ sudo find /bin /sbin /usr/bin /usr/sbin /usr/local/bin /usr/local/sbin -perm /022 -type f -exec chmod 755 '{}' \;

Ubuntu 24.04 LTS must have system commands owned by root or a system account.

STIG ID: UBTU-24-300012 | SRG: SRG-OS-000259-GPOS-00100 | Severity: medium | CCI: CCI-001499 | Vulnerability Id: V-270702

Vulnerability Discussion

If Ubuntu 24.04 LTS were to allow any user to make changes to software libraries, then those changes might be implemented without undergoing the appropriate testing and approvals that are part of a robust change management process.

This requirement applies to Ubuntu 24.04 LTS with software libraries that are accessible and configurable, as in the case of interpreted languages. Software libraries also include privileged programs that execute with escalated privileges. Only qualified and authorized individuals must be allowed to obtain access to information system components for purposes of initiating changes, including upgrades and modifications.

Check

Verify the system commands contained in the following directories are owned by root, or a required system account, with the following command:

$ sudo find /bin /sbin /usr/bin /usr/sbin /usr/local/bin /usr/local/sbin ! -user root -type f -exec stat -c "%n %U" '{}' \;

If any system commands are returned and not owned by a required system account, this is a finding.

Fix

Configure the system commands and their respective parent directories to be protected from unauthorized access. Run the following command, replacing "[FILE]" with any system command file not owned by "root" or a required system account:

$ sudo chown root [FILE]

Ubuntu 24.04 LTS must have system commands group-owned by root or a system account.

STIG ID: UBTU-24-300013 | SRG: SRG-OS-000259-GPOS-00100 | Severity: medium | CCI: CCI-001499 | Vulnerability Id: V-270703

Vulnerability Discussion

If Ubuntu 24.04 LTS were to allow any user to make changes to software libraries, then those changes might be implemented without undergoing the appropriate testing and approvals that are part of a robust change management process.

This requirement applies to Ubuntu 24.04 LTS with software libraries that are accessible and configurable, as in the case of interpreted languages. Software libraries also include privileged programs that execute with escalated privileges. Only qualified and authorized individuals must be allowed to obtain access to information system components for purposes of initiating changes, including upgrades and modifications.

Check

Verify the system commands contained in the following directories are group-owned by root or a required system account with the following command:

$ find /bin /sbin /usr/bin /usr/sbin /usr/local/bin /usr/local/sbin \-type f -perm -u=x -exec stat --format="%n %G" {} + | \awk '$2 != "root" && $2 != "daemon" && $2 != "adm" && $2 != "shadow" && $2 != "mail" && $2 != "crontab" && $2 != "_ssh"'

Note: The above command uses awk to filter out common system accounts. If your system uses other required system accounts, add them to the awk condition to filter them out of the results.

If any system commands are returned that are not group-owned by a required system account, this is a finding.

Fix

Configure the system commands to be protected from unauthorized access. Run the following command, replacing "[FILE]" with any system command file not group-owned by "root" or a required system account:

$ sudo chgrp [SYSTEMACCOUNT] [FILE]

Ubuntu 24.04 LTS must prevent the use of dictionary words for passwords.

STIG ID: UBTU-24-300014 | SRG: SRG-OS-000710-GPOS-00160 | Severity: medium | CCI: CCI-004061 | Vulnerability Id: V-270704

Vulnerability Discussion

Password-based authentication applies to passwords regardless of whether they are used in single-factor or multifactor authentication. Long passwords or passphrases are preferable over shorter passwords. Enforced composition rules provide marginal security benefits while decreasing usability. However, organizations may choose to establish certain rules for password generation (e.g., minimum character length for long passwords) under certain circumstances and can enforce this requirement in IA-5(1)(h). Account recovery can occur, for example, in situations when a password is forgotten. Cryptographically protected passwords include salted one-way cryptographic hashes of passwords. The list of commonly used, compromised, or expected passwords includes passwords obtained from previous breach corpuses, dictionary words, and repetitive or sequential characters. The list includes context-specific words, such as the name of the service, username, and derivatives thereof.

Check

Verify Ubuntu 24.04 LTS uses the "cracklib" library to prevent the use of dictionary words with the following command:

$ grep dictcheck /etc/security/pwquality.conf
dictcheck=1

If the "dictcheck" parameter is not set to "1" or is commented out, this is a finding.

Fix

Configure Ubuntu 24.04 LTS to prevent the use of dictionary words for passwords.

Add or update the following line in the "/etc/security/pwquality.conf" file to include the "dictcheck=1" parameter:

dictcheck=1

Ubuntu 24.04 LTS must be configured so that when passwords are changed or new passwords are established, pwquality must be used.

STIG ID: UBTU-24-300016 | SRG: SRG-OS-000480-GPOS-00225 | Severity: medium | CCI: CCI-000366 | Vulnerability Id: V-270705

Vulnerability Discussion

Use of a complex password helps to increase the time and resources required to compromise the password. Password complexity, or strength, is a measure of the effectiveness of a password in resisting attempts at guessing and brute-force attacks. "pwquality" enforces complex password construction configuration and has the ability to limit brute-force attacks on the system.

Check

Verify that Ubuntu 24.04 LTS uses "pwquality" to enforce the password complexity rules.

Verify the pwquality module is being enforced by Ubuntu 24.04 LTS with the following command:

$ grep -i enforcing /etc/security/pwquality.conf
enforcing = 1

If the value of "enforcing" is not "1", or the line is commented out, this is a finding.

Check for the use of "pwquality" with the following command:

$ cat /etc/pam.d/common-password | grep requisite | grep pam_pwquality
password requisite pam_pwquality.so retry=3

If the value of "retry" is set to "0" or is greater than "3", or if a line is not returned, this is a finding.

Fix

Configure Ubuntu 24.04 LTS to use "pwquality" to enforce password complexity rules.

Add the following line to "/etc/security/pwquality.conf" (or modify the line to have the required value):

enforcing = 1

Add the following line to "/etc/pam.d/common-password" (or modify the line to have the required value):

password requisite pam_pwquality.so retry=3

Note: Ensure the value of "retry" is between "1" and "3".

Ubuntu 24.04 LTS must enforce a delay of at least four seconds between logon prompts following a failed logon attempt.

STIG ID: UBTU-24-300017 | SRG: SRG-OS-000480-GPOS-00226 | Severity: low | CCI: CCI-000366 | Vulnerability Id: V-270706

Vulnerability Discussion

Limiting the number of logon attempts over a certain time interval reduces the chances that an unauthorized user may gain access to an account.

The delay option is set in microseconds.

Check

Verify Ubuntu 24.04 LTS enforces a delay of at least four seconds between logon prompts following a failed logon attempt with the following command:

$ grep pam_faildelay /etc/pam.d/common-auth
auth required pam_faildelay.so delay=4000000

If the value for "delay" is not set to "4000000" or greater, the line is commented out, or is missing, this is a finding.

Fix

Configure Ubuntu 24.04 LTS to enforce a delay of at least four seconds between logon prompts following a failed logon attempt.

Edit the file "/etc/pam.d/common-auth" and set the parameter "pam_faildelay" to a value of "4000000" or greater:

auth required pam_faildelay.so delay=4000000

Ubuntu 24.04 LTS must require users to reauthenticate for privilege escalation or when changing roles.

STIG ID: UBTU-24-300021 | SRG: SRG-OS-000480-GPOS-00227 | Severity: medium | CCI: CCI-000366 | Vulnerability Id: V-270707

Vulnerability Discussion

Without reauthentication, users may access resources or perform tasks for which they do not have authorization.

When operating systems provide the capability to escalate a functional capability, it is critical the user reauthenticate.

Check

Verify the "/etc/sudoers" file has no occurrences of "NOPASSWD" or "!authenticate" with the following command:

$ sudo egrep -i '(nopasswd|!authenticate)' /etc/sudoers /etc/sudoers.d/*

If any occurrences of "NOPASSWD" or "!authenticate" return from the command, this is a finding.

Fix

Remove any occurrence of "NOPASSWD" or "!authenticate" found in "/etc/sudoers" file or files in the "/etc/sudoers.d" directory.

Ubuntu 24.04 LTS must be configured so that remote X connections are disabled, unless to fulfill documented and validated mission requirements.

STIG ID: UBTU-24-300022 | SRG: SRG-OS-000480-GPOS-00227 | Severity: high | CCI: CCI-000366 | Vulnerability Id: V-270708

Vulnerability Discussion

The security risk of using X11 forwarding is that the client's X11 display server may be exposed to attack when the SSH client requests forwarding. A system administrator (SA) must protect clients that may expose themselves to attack by unwittingly requesting X11 forwarding, which can warrant a ''no'' setting.

X11 forwarding must be enabled with caution. Users with the ability to bypass file permissions on the remote host (for the user's X11 authorization database) can access the local X11 display through the forwarded connection. An attacker may then be able to perform activities such as keystroke monitoring if the ForwardX11Trusted option is also enabled.

If X11 services are not required for the system's intended function, they must be disabled or restricted as appropriate to the system's needs.

Check

Verify that X11Forwarding is disabled with the following command:

$ sudo grep -ir x11forwarding /etc/ssh/sshd_config* | grep -v "^#"
X11Forwarding no

If the "X11Forwarding" keyword is set to "yes" and is not documented with the information system security officer (ISSO) as an operational requirement, is missing, or multiple conflicting results are returned, this is a finding.

Fix

Edit the "/etc/ssh/sshd_config" file to uncomment or add the line for the "X11Forwarding" keyword and set its value to "no" (this file may be named differently or be in a different location if using a version of SSH that is provided by a third-party vendor):

X11Forwarding no

Restart the SSH daemon for the changes to take effect:

$ sudo systemctl restart sshd.service

Ubuntu 24.04 LTS SSH daemon must prevent remote hosts from connecting to the proxy display.

STIG ID: UBTU-24-300023 | SRG: SRG-OS-000480-GPOS-00227 | Severity: medium | CCI: CCI-000366 | Vulnerability Id: V-270709

Vulnerability Discussion

When X11 forwarding is enabled, there may be additional exposure to the server and client displays if the sshd proxy display is configured to listen on the wildcard address. By default, sshd binds the forwarding server to the loopback address and sets the hostname part of the DISPLAY environment variable to localhost. This prevents remote hosts from connecting to the proxy display.

Check

Verify the SSH daemon prevents remote hosts from connecting to the proxy display with the following command:

$ sudo grep -ir x11uselocalhost /etc/ssh/sshd_config*
X11UseLocalhost yes

If the "X11UseLocalhost" keyword is set to "no", is commented out, is missing, or multiple conflicting results are returned, this is a finding.

Fix

Configure the SSH daemon to prevent remote hosts from connecting to the proxy display.

Edit the "/etc/ssh/sshd_config" file to uncomment or add the line for the "X11UseLocalhost" keyword and set its value to "yes" (this file may be named differently or be in a different location if using a version of SSH that is provided by a third-party vendor):

X11UseLocalhost yes

Restart the SSH daemon for the changes to take effect:

$ sudo systemctl restart sshd.service

Ubuntu 24.04 LTS must display the date and time of the last successful account logon upon logon.

STIG ID: UBTU-24-300024 | SRG: SRG-OS-000480-GPOS-00227 | Severity: low | CCI: CCI-000366 | Vulnerability Id: V-270710

Vulnerability Discussion

Configuration settings are the set of parameters that can be changed in hardware, software, or firmware components of the system that affect the security posture and/or functionality of the system. Security-related parameters are those parameters impacting the security state of the system, including the parameters required to satisfy other security control requirements. Security-related parameters include, for example, registry settings; account, file, directory permission settings; and settings for functions, ports, protocols, services, and remote connections.

Check

Verify users are provided with feedback on when account accesses last occurred with the following command:

$ grep pam_lastlog /etc/pam.d/login
session required pam_lastlog.so showfailed

If the line containing "pam_lastlog" is not set to "required", or the "silent" option is present, or the line is commented out, or the line is missing , this is a finding.

Fix

Configure Ubuntu 24.04 LTS to provide users with feedback on when account accesses last occurred by setting the required configuration options in "/etc/pam.d/login".

Add the following line to the top of "/etc/pam.d/login":

session required pam_lastlog.so showfailed

Ubuntu 24.04 LTS must disable the x86 Ctrl-Alt-Delete key sequence if a graphical user interface is installed.

STIG ID: UBTU-24-300025 | SRG: SRG-OS-000480-GPOS-00227 | Severity: high | CCI: CCI-000366 | Vulnerability Id: V-270711

Vulnerability Discussion

A locally logged-on user who presses Ctrl-Alt-Delete, when at the console, can reboot the system. If accidentally pressed, as could happen in the case of a mixed OS environment, this can create the risk of short-term loss of availability of systems due to unintentional reboot. In the graphical environment, risk of unintentional reboot from the Ctrl-Alt-Delete sequence is reduced because the user will be prompted before any action is taken.

Check

Verify Ubuntu 24.04 LTS is not configured to reboot the system when Ctrl-Alt-Delete is pressed when using a graphical user interface with the following command:

$ gsettings get org.gnome.settings-daemon.plugins.media-keys logout
@as []

If the "logout" key is bound to an action, is commented out, or is missing, this is a finding.

Fix

Configure the system to disable the Ctrl-Alt-Delete sequence when using a graphical user interface.

gsettings set org.gnome.settings-daemon.plugins.media-keys logout []

Update the dconf settings:

$ sudo dconf update

Ubuntu 24.04 LTS must disable the x86 Ctrl-Alt-Delete key sequence.

STIG ID: UBTU-24-300026 | SRG: SRG-OS-000480-GPOS-00227 | Severity: high | CCI: CCI-000366 | Vulnerability Id: V-270712

Vulnerability Discussion

Check

Verify Ubuntu 24.04 LTS is not configured to reboot the system when Ctrl-Alt-Delete is pressed with the following command:

$ systemctl status ctrl-alt-del.target
o ctrl-alt-del.target
Loaded: masked (Reason: Unit ctrl-alt-del.target is masked.)
Active: inactive (dead)

If the "ctrl-alt-del.target" is not masked, this is a finding.

Fix

Configure the system to disable the Ctrl-Alt-Delete sequence for the command line with the following commands:

$ sudo systemctl disable ctrl-alt-del.target
[...]

$ sudo systemctl mask ctrl-alt-del.target
Created symlink /etc/systemd/system/ctrl-alt-del.target ? /dev/null.

Reload the daemon to take effect:

$ sudo systemctl daemon-reload

Ubuntu 24.04 LTS must not have accounts configured with blank or null passwords.

STIG ID: UBTU-24-300027 | SRG: SRG-OS-000480-GPOS-00227 | Severity: high | CCI: CCI-000366 | Vulnerability Id: V-270713

Vulnerability Discussion

If an account has an empty password, anyone could log on and run commands with the privileges of that account. Accounts with empty passwords must never be used in operational environments.

Check

Check the "/etc/shadow" file for blank passwords with the following command:

$ sudo awk -F: '!$2 {print $1}' /etc/shadow

If the command returns any results, this is a finding.

Fix

Configure all accounts on the system to have a password or lock the account with the following commands:

Perform a password reset:
$ sudo passwd [username]

Lock an account:
$ sudo passwd -l [username]

Ubuntu 24.04 LTS must not allow accounts configured in Pluggable Authentication Modules (PAM) with blank or null passwords.

STIG ID: UBTU-24-300028 | SRG: SRG-OS-000480-GPOS-00227 | Severity: high | CCI: CCI-000366 | Vulnerability Id: V-270714

Vulnerability Discussion

If an account has an empty password, anyone could log on and run commands with the privileges of that account. Accounts with empty passwords must never be used in operational environments.

Check

To verify null passwords cannot be used, run the following command:

$ grep nullok /etc/pam.d/common-password

If this produces any output, this is a finding.

Fix

If an account is configured for password authentication but does not have an assigned password, it is possible to log on to the account without authenticating.

Remove any instances of the "nullok" option in "/etc/pam.d/common-password" to prevent logons with empty passwords.

Ubuntu 24.04 LTS must generate audit records for all events that affect the systemd journal files.

STIG ID: UBTU-24-300029 | SRG: SRG-OS-000480-GPOS-00227 | Severity: medium | CCI: CCI-000366 | Vulnerability Id: V-270715

Vulnerability Discussion

Once an attacker establishes access to a system, the attacker often attempts to create a persistent method of reestablishing access. One way to accomplish this is for the attacker to modify system level binaries and their operation. Auditing the systemd journal files provides logging that can be used for forensic purposes.

To address access requirements, many operating systems may be integrated with enterprise-level authentication/access/auditing mechanisms that meet or exceed access control policy requirements.

Check

Verify Ubuntu 24.04 LTS generates audit records for all events that affect "/var/log/journal" with the following command:

$ sudo auditctl -l | grep journal
-w /var/log/journal -p wa -k systemd_journal

If the command does not return a line that matches the example or the line is commented out, this is a finding.

Note: The "-k" allows for specifying an arbitrary identifier, and the string after it does not need to match the example output above.

Fix

Configure Ubuntu 24.04 LTS to generate audit records for events that affect "/var/log/journal".

Add or update the following rule to "/etc/audit/rules.d/stig.rules":

-w /var/log/journal -p wa -k systemd_journal

To reload the rules file, issue the following command:

$ sudo augenrules --load

Ubuntu 24.04 LTS default filesystem permissions must be defined in such a way that all authenticated users can read and modify only their own files.

STIG ID: UBTU-24-300030 | SRG: SRG-OS-000480-GPOS-00228 | Severity: medium | CCI: CCI-000366 | Vulnerability Id: V-270716

Vulnerability Discussion

Setting the most restrictive default permissions ensures that when new accounts are created, they do not have unnecessary access.

Check

Verify Ubuntu 24.04 LTS defines default permissions for all authenticated users in such a way that the user can read and modify only their own files with the following command:

$ grep -i '^\s*umask' /etc/login.defs
UMASK 077

If the "UMASK" variable is set to "000", this is a finding with the severity raised to a CAT I.

If the value of "UMASK" is not set to "077", is commented out, or is missing, this is a finding.

Fix

Configure the system to define the default permissions for all authenticated users in such a way that the user can read and modify only their own files.

Edit the "UMASK" parameter in the "/etc/login.defs" file to match the example below:

UMASK 077

Ubuntu 24.04 LTS must not allow unattended or automatic login via SSH.

STIG ID: UBTU-24-300031 | SRG: SRG-OS-000480-GPOS-00229 | Severity: high | CCI: CCI-000366 | Vulnerability Id: V-270717

Vulnerability Discussion

Failure to restrict system access to authenticated users negatively impacts Ubuntu 24.04 LTS security.

Check

Verify unattended or automatic login via SSH is disabled with the following command:

$ egrep -r '(Permit(.*?)(Passwords|Environment))' /etc/ssh/sshd_config
PermitEmptyPasswords no
PermitUserEnvironment no

If the "PermitEmptyPasswords" or "PermitUserEnvironment" keywords are set to a value other than "no", are commented out, are both missing, or conflicting results are returned, this is a finding.

Fix

Configure Ubuntu 24.04 LTS to allow the SSH daemon to not allow unattended or automatic login to the system.

Add or edit the following lines in the "/etc/ssh/sshd_config" file:

PermitEmptyPasswords no
PermitUserEnvironment no

Restart the SSH daemon for the changes to take effect:

$ sudo systemctl restart sshd.service

Ubuntu 24.04 LTS must disable automatic mounting of Universal Serial Bus (USB) mass storage driver.

STIG ID: UBTU-24-300039 | SRG: SRG-OS-000690-GPOS-00140 | Severity: medium | CCI: CCI-003959,CCI-001958 | Vulnerability Id: V-270718

Vulnerability Discussion

Without authenticating devices, unidentified or unknown devices may be introduced, thereby facilitating malicious activity.

Peripherals include, but are not limited to, devices such as flash drives, external storage, and printers.

Satisfies: SRG-OS-000690-GPOS-00140, SRG-OS-000378-GPOS-00163

Check

Verify that Ubuntu 24.04 LTS disables ability to load the USB storage kernel module with the following command:

$ sudo grep usb-storage /etc/modprobe.d/* | grep "/bin/true"
/etc/modprobe.d/DISASTIG.conf:install usb-storage /bin/true

If the command does not return any output, or the line is commented out, this is a finding.

Verify Ubuntu 24.04 LTS disables the ability to use USB mass storage device.

$ sudo grep usb-storage /etc/modprobe.d/* | grep -i "blacklist"
/etc/modprobe.d/DISASTIG.conf:blacklist usb-storage

If the command does not return any output, or the line is commented out, this is a finding.

Fix

Configure Ubuntu 24.04 LTS to disable using the USB storage kernel module with the following command:

$ sudo su -c "echo install usb-storage /bin/true >> /etc/modprobe.d/DISASTIG.conf"

Configure Ubuntu 24.04 LTS to disable the ability to use USB mass storage devices with the following command:

$ sudo su -c "echo blacklist usb-storage >> /etc/modprobe.d/DISASTIG.conf"

Ubuntu 24.04 LTS must be configured to prohibit or restrict the use of functions, ports, protocols, and/or services, as defined in the Ports, Protocols, and Services Management Category Assurance List (PPSM CAL) and vulnerability assessments.

STIG ID: UBTU-24-300041 | SRG: SRG-OS-000096-GPOS-00050 | Severity: medium | CCI: CCI-000382 | Vulnerability Id: V-270719

Vulnerability Discussion

To prevent unauthorized connection of devices, unauthorized transfer of information, or unauthorized tunneling (i.e., embedding of data types within data types), organizations must disable or restrict unused or unnecessary physical and logical ports/protocols on information systems.

Operating systems are capable of providing a wide variety of functions and services. Some of the functions and services provided by default may not be necessary to support essential organizational operations. Additionally, it is sometimes convenient to provide multiple services from a single component (e.g., VPN and IPS); however, doing so increases risk over limiting the services provided by any one component.

To support the requirements and principles of least functionality, Ubuntu 24.04 LTS must support the organizational requirements, providing only essential capabilities and limiting the use of ports, protocols, and/or services to only those required, authorized, and approved to conduct official business or to address authorized quality of life issues.

Check

Check the firewall configuration for any unnecessary or prohibited functions, ports, protocols, and/or services with the following command:

$ sudo ufw show raw
Chain OUTPUT (policy ACCEPT)
target prot opt sources destination
Chain INPUT (policy ACCEPT 1 packets, 40 bytes)
pkts bytes target prot opt in out source destination

Chain FORWARD (policy ACCEPT 0 packets, 0 bytes)
pkts bytes target prot opt in out source destination

Chain OUTPUT (policy ACCEPT 0 packets, 0 bytes)
pkts bytes target prot opt in out source destination

Ask the system administrator for the site or program PPSM Components Local Services Assessment (CLSA). Verify the services allowed by the firewall match the PPSM CLSA.

If there are any additional ports, protocols, or services that are not included in the PPSM CLSA, this is a finding.

If there are any ports, protocols, or services that are prohibited by the PPSM CAL, this is a finding.

Fix

Add all ports, protocols, or services allowed by the PPSM CLSA by using the following command:

$ sudo ufw allow <direction> <port/protocol/service>

Where the direction is "in" or "out" and the port is the one corresponding to the protocol or service allowed.

To deny access to ports, protocols, or services, use:

$ sudo ufw deny <direction> <port/protocol/service>

Ubuntu 24.04 LTS must uniquely identify interactive users.

STIG ID: UBTU-24-400000 | SRG: SRG-OS-000104-GPOS-00051 | Severity: medium | CCI: CCI-000764,CCI-000804 | Vulnerability Id: V-270720

Vulnerability Discussion

To ensure accountability and prevent unauthenticated access, organizational users must be identified and authenticated to prevent potential misuse and compromise of the system.

Organizational users include organizational employees or individuals the organization deems to have equivalent status of employees (e.g., contractors). Organizational users (and processes acting on behalf of users) must be uniquely identified and authenticated to all accesses, except for the following:

1) Accesses explicitly identified and documented by the organization. Organizations document specific user actions that can be performed on the information system without identification or authentication; and

2) Accesses that occur through authorized use of group authenticators without individual authentication. Organizations may require unique identification of individuals in group accounts (e.g., shared privilege accounts) or for detailed accountability of individual activity.

Satisfies: SRG-OS-000104-GPOS-00051, SRG-OS-000121-GPOS-00062

Check

Verify Ubuntu 24.04 LTS contains no duplicate User IDs (UIDs) for interactive users with the following command:

$ awk -F ":" 'list[$3]++{print $1, $3}' /etc/passwd

If output is produced and the accounts listed are interactive user accounts, this is a finding.

Fix

Edit the file "/etc/passwd" and provide each interactive user account that has a duplicate UID with a unique UID.

Ubuntu 24.04 LTS must implement smart card logins for multifactor authentication for local and network access to privileged and nonprivileged accounts.

STIG ID: UBTU-24-400020 | SRG: SRG-OS-000105-GPOS-00052 | Severity: medium | CCI: CCI-000765,CCI-000766 | Vulnerability Id: V-270721

Vulnerability Discussion

Without the use of multifactor authentication, the ease of access to privileged functions is greatly increased.

Multifactor authentication requires using two or more factors to achieve authentication.

Factors include:
1) Something a user knows (e.g., password/PIN);
2) Something a user has (e.g., cryptographic identification device, token); and
3) Something a user is (e.g., biometric).

A privileged account is defined as an information system account with authorizations of a privileged user.

Network access is defined as access to an information system by a user (or a process acting on behalf of a user) communicating through a network (e.g., local area network, wide area network, or the internet).

The DOD common access card (CAC) with DOD-approved PKI is an example of multifactor authentication.

Satisfies: SRG-OS-000105-GPOS-00052, SRG-OS-000107-GPOS-00054, SRG-OS-000106-GPOS-00053, SRG-OS-000108-GPOS-00055

Check

Verify that the "pam_pkcs11.so" module is configured with the following command:

$ grep -r pam_pkcs11.so /etc/pam.d/common-auth
auth [success=2 default=ignore] pam_pkcs11.so

If the module is not configured, is missing, or commented out, this is a finding.

Fix

Configure Ubuntu 24.04 LTS to use multifactor authentication for access to accounts.

Add or update "pam_pkcs11.so" in "/etc/pam.d/common-auth" to match the following line:

auth [success=2 default=ignore] pam_pkcs11.so

Ubuntu 24.04 LTS must implement smart card logins for multifactor authentication for local and network access to privileged and nonprivileged accounts over SSH.

STIG ID: UBTU-24-400030 | SRG: SRG-OS-000105-GPOS-00052 | Severity: medium | CCI: CCI-000765,CCI-000766 | Vulnerability Id: V-270722

Vulnerability Discussion

Without the use of multifactor authentication, the ease of access to privileged functions is greatly increased.

Multifactor authentication requires using two or more factors to achieve authentication.

Factors include:
1) Something a user knows (e.g., password/PIN);
2) Something a user has (e.g., cryptographic identification device, token); and
3) Something a user is (e.g., biometric).

A privileged account is defined as an information system account with authorizations of a privileged user.

Network access is defined as access to an information system by a user (or a process acting on behalf of a user) communicating through a network (e.g., local area network, wide area network, or the internet).

The DOD common access card (CAC) with DOD-approved PKI is an example of multifactor authentication.

Satisfies: SRG-OS-000105-GPOS-00052, SRG-OS-000107-GPOS-00054, SRG-OS-000106-GPOS-00053, SRG-OS-000108-GPOS-00055

Check

Verify the sshd daemon allows public key authentication with the following command:

$ sudo grep -r ^PubkeyAuthentication /etc/ssh/sshd_config*
/etc/ssh/sshd_config:PubkeyAuthentication yes

If "PubkeyAuthentication" is not set to "yes", is commented out, is missing, or conflicting results are returned, this is a finding.

Fix

Configure Ubuntu 24.04 LTS to use multifactor authentication for access to accounts.

Set the sshd option "PubkeyAuthentication" to "yes" in the "/etc/ssh/sshd_config" file.

PubkeyAuthentication yes

Ubuntu 24.04 LTS must electronically verify Personal Identity Verification (PIV) credentials.

STIG ID: UBTU-24-400060 | SRG: SRG-OS-000377-GPOS-00162 | Severity: medium | CCI: CCI-001954 | Vulnerability Id: V-270723

Vulnerability Discussion

Check

Verify Ubuntu 24.04 LTS electronically verifies PIV credentials via certificate status checking with the following command:

$ sudo grep use_pkcs11_module /etc/pam_pkcs11/pam_pkcs11.conf | awk '/pkcs11_module opensc {/,/}/' /etc/pam_pkcs11/pam_pkcs11.conf | grep cert_policy | grep ocsp_on

cert_policy = ca,signature,ocsp_on;

If every returned "cert_policy" line is not set to "ocsp_on", or the line is commented out, this is a finding.

Fix

Configure Ubuntu 24.04 LTS to do certificate status checking for multifactor authentication.

Modify all of the "cert_policy" lines in "/etc/pam_pkcs11/pam_pkcs11.conf" to include "ocsp_on".

Ubuntu 24.04 LTS must prevent direct login to the root account.

STIG ID: UBTU-24-400110 | SRG: SRG-OS-000109-GPOS-00056 | Severity: medium | CCI: CCI-004045 | Vulnerability Id: V-270724

Vulnerability Discussion

To ensure individual accountability and prevent unauthorized access, organizational users must be individually identified and authenticated.

A group authenticator is a generic account used by multiple individuals. Use of a group authenticator alone does not uniquely identify individual users. Examples of the group authenticator are the Unix OS "root" user account, the Windows "Administrator" account, the "sa" account, or a "helpdesk" account.

For example, the Unix and Windows operating systems offer a "switch user" capability allowing users to authenticate with their individual credentials and, when needed, switch to the administrator role. This method provides for unique individual authentication prior to using a group authenticator.

Users (and any processes acting on behalf of users) need to be uniquely identified and authenticated for all accesses other than those accesses explicitly identified and documented by the organization, which outlines specific user actions that can be performed on Ubuntu 24.04 LTS without identification or authentication.

Requiring individuals to be authenticated with an individual authenticator prior to using a group authenticator allows for traceability of actions, as well as adding an additional level of protection of the actions that can be taken with group account knowledge.

Check

Verify Ubuntu 24.04 LTS prevents direct logins to the root account with the following command:

$ sudo passwd -S root
root L 04/08/2024 0 99999 7 -1

If the output does not contain "L" in the second field to indicate the account is locked, this is a finding.

Fix

Configure Ubuntu 24.04 LTS to prevent direct logins to the root account by performing the following operations:

$ sudo passwd -l root

Ubuntu 24.04 LTS must store only encrypted representations of passwords.

STIG ID: UBTU-24-400220 | SRG: SRG-OS-000073-GPOS-00041 | Severity: medium | CCI: CCI-004062 | Vulnerability Id: V-270725

Vulnerability Discussion

Password complexity, or strength, is a measure of the effectiveness of a password in resisting attempts at guessing and brute-force attacks. If the information system or application allows the user to consecutively reuse their password when that password has exceeded its defined lifetime, the end result is a password that is not changed per policy requirements.

Check

Verify the Ubuntu operating system stores only encrypted representations of passwords with the following command:

$ grep pam_unix.so /etc/pam.d/common-password
password [success=1 default=ignore] pam_unix.so obscure sha512 shadow remember=5 rounds=100000

If the "sha512" parameter value is missing from the "pam_unix.so" line, this is a finding.

Fix

Configure Ubuntu 24.04 LTS to store encrypted representations of passwords.

Add or modify the "sha512" parameter value to the following line in "/etc/pam.d/common-password" file:

password [success=1 default=ignore] pam_unix.so obscure sha512 shadow remember=5 rounds=100000

Ubuntu 24.04 LTS must enforce password complexity by requiring that at least one uppercase character be used.

STIG ID: UBTU-24-400260 | SRG: SRG-OS-000069-GPOS-00037 | Severity: medium | CCI: CCI-004065,CCI-004066 | Vulnerability Id: V-270726

Vulnerability Discussion

Use of a complex password helps to increase the time and resources required to compromise the password. Password complexity, or strength, is a measure of the effectiveness of a password in resisting attempts at guessing and brute-force attacks.

Password complexity is one factor of several that determines how long it takes to crack a password. The more complex the password, the greater the number of possible combinations that need to be tested before the password is compromised.

Satisfies: SRG-OS-000069-GPOS-00037, SRG-OS-000730-GPOS-00190

Check

Verify Ubuntu 24.04 LTS enforces password complexity by requiring that at least one uppercase character be used with the following command:

$ grep -i "ucredit" /etc/security/pwquality.conf
ucredit=-1

If the "ucredit" parameter is greater than "-1", is commented out, or is missing, this is a finding.

Fix

Configure Ubuntu 24.04 LTS to enforce password complexity by requiring that at least one uppercase character be used.

Add or update the "/etc/security/pwquality.conf" file to contain the "ucredit" parameter:

ucredit=-1

Ubuntu 24.04 LTS must enforce password complexity by requiring that at least one lowercase character be used.

STIG ID: UBTU-24-400270 | SRG: SRG-OS-000070-GPOS-00038 | Severity: medium | CCI: CCI-004065,CCI-004066 | Vulnerability Id: V-270727

Vulnerability Discussion

Use of a complex password helps to increase the time and resources required to compromise the password. Password complexity, or strength, is a measure of the effectiveness of a password in resisting attempts at guessing and brute-force attacks.

Password complexity is one factor of several that determines how long it takes to crack a password. The more complex the password, the greater the number of possible combinations that need to be tested before the password is compromised.

Satisfies: SRG-OS-000070-GPOS-00038, SRG-OS-000730-GPOS-00190

Check

Verify Ubuntu 24.04 LTS enforces password complexity by requiring that at least one lowercase character be used with the following command:

$ grep -i "lcredit" /etc/security/pwquality.conf
lcredit=-1

If the "lcredit" parameter is greater than "-1", is commented out, or is missing, this is a finding.

Fix

Configure Ubuntu 24.04 LTS to enforce password complexity by requiring that at least one lowercase character be used.

Add or update the "/etc/security/pwquality.conf" file to contain the "lcredit" parameter:

lcredit=-1

Ubuntu 24.04 LTS must enforce password complexity by requiring that at least one numeric character be used.

STIG ID: UBTU-24-400280 | SRG: SRG-OS-000071-GPOS-00039 | Severity: medium | CCI: CCI-004065,CCI-004066 | Vulnerability Id: V-270728

Vulnerability Discussion

Use of a complex password helps to increase the time and resources required to compromise the password. Password complexity, or strength, is a measure of the effectiveness of a password in resisting attempts at guessing and brute-force attacks.

Password complexity is one factor of several that determines how long it takes to crack a password. The more complex the password, the greater the number of possible combinations that need to be tested before the password is compromised.

Satisfies: SRG-OS-000071-GPOS-00039, SRG-OS-000730-GPOS-00190

Check

Verify Ubuntu 24.04 LTS enforces password complexity by requiring that at least one numeric character be used.

Determine if the field "dcredit" is set in the "/etc/security/pwquality.conf" file with the following command:

$ grep -i "dcredit" /etc/security/pwquality.conf
dcredit=-1

If the "dcredit" parameter is greater than "-1", is commented out, or is missing, this is a finding.

Fix

Configure Ubuntu 24.04 LTS to enforce password complexity by requiring that at least one numeric character be used.

Add or update the "/etc/security/pwquality.conf" file to contain the "dcredit" parameter:

dcredit=-1

Ubuntu 24.04 LTS must require the change of at least eight characters when passwords are changed.

STIG ID: UBTU-24-400290 | SRG: SRG-OS-000072-GPOS-00040 | Severity: medium | CCI: CCI-004065,CCI-004066 | Vulnerability Id: V-270729

Vulnerability Discussion

If Ubuntu 24.04 LTS allows the user to consecutively reuse extensive portions of passwords, this increases the chances of password compromise by increasing the window of opportunity for attempts at guessing and brute-force attacks.

The number of changed characters refers to the number of changes required with respect to the total number of positions in the current password. In other words, characters may be the same within the two passwords; however, the positions of the like characters must be different.

If the password length is an odd number, then number of changed characters must be rounded up. For example, a password length of 15 characters must require the change of at least eight characters.

Satisfies: SRG-OS-000072-GPOS-00040, SRG-OS-000730-GPOS-00190

Check

Verify Ubuntu 24.04 LTS requires the change of at least eight characters when passwords are changed with the following command:

$ grep -i "difok" /etc/security/pwquality.conf
difok=8

If the "difok" parameter is less than "8" or is commented out, this is a finding.

Fix

Configure Ubuntu 24.04 LTS to require the change of at least eight characters when passwords are changed.

Add or update the "/etc/security/pwquality.conf" file to include the "difok=8" parameter:

difok=8

Ubuntu 24.04 LTS must enforce 24 hours/1 day as the minimum password lifetime. Passwords for new users must have a 24 hours/1 day minimum password lifetime restriction.

STIG ID: UBTU-24-400300 | SRG: SRG-OS-000075-GPOS-00043 | Severity: medium | CCI: CCI-004065,CCI-004066 | Vulnerability Id: V-270730

Vulnerability Discussion

Enforcing a minimum password lifetime helps to prevent repeated password changes to defeat the password reuse or history enforcement requirement. If users are allowed to immediately and continually change their password, then the password could be repeatedly changed in a short period of time to defeat the organization's policy regarding password reuse.

Satisfies: SRG-OS-000075-GPOS-00043, SRG-OS-000730-GPOS-00190

Check

Verify Ubuntu 24.04 LTS enforces a 24 hours/1 day minimum password lifetime for new user accounts with the following command:

$ grep -i ^PASS_MIN_DAYS /etc/login.defs
PASS_MIN_DAYS 1

If the "PASS_MIN_DAYS" parameter value is less than "1" or is commented out, this is a finding.

Fix

Configure Ubuntu 24.04 LTS to enforce a 24 hours/1 day minimum password lifetime.

Add or modify the following line in the "/etc/login.defs" file:

PASS_MIN_DAYS 1

Ubuntu 24.04 LTS must enforce a 60-day maximum password lifetime restriction. Passwords for new users must have a 60-day maximum password lifetime restriction.

STIG ID: UBTU-24-400310 | SRG: SRG-OS-000076-GPOS-00044 | Severity: medium | CCI: CCI-004065,CCI-004066 | Vulnerability Id: V-270731

Vulnerability Discussion

Any password, no matter how complex, can eventually be cracked. Therefore, passwords need to be changed periodically. If Ubuntu 24.04 LTS does not limit the lifetime of passwords and force users to change their passwords, there is the risk that Ubuntu 24.04 LTS passwords could be compromised.

Satisfies: SRG-OS-000076-GPOS-00044, SRG-OS-000730-GPOS-00190

Check

Verify Ubuntu 24.04 LTS enforces a 60-day maximum password lifetime for new user accounts with the following command:

$ grep -i ^PASS_MAX_DAYS /etc/login.defs
PASS_MAX_DAYS 60

If the "PASS_MAX_DAYS" parameter value is less than "60" or is commented out, this is a finding.

Fix

Configure Ubuntu 24.04 LTS to enforce a 60-day maximum password lifetime.

Add or modify the following line in the "/etc/login.defs" file:

PASS_MAX_DAYS 60

Ubuntu 24.04 LTS must enforce a minimum 15-character password length.

STIG ID: UBTU-24-400320 | SRG: SRG-OS-000078-GPOS-00046 | Severity: medium | CCI: CCI-004065,CCI-004066 | Vulnerability Id: V-270732

Vulnerability Discussion

The shorter the password, the lower the number of possible combinations that need to be tested before the password is compromised.

Password complexity, or strength, is a measure of the effectiveness of a password in resisting attempts at guessing and brute-force attacks. Password length is one factor of several that helps to determine strength and how long it takes to crack a password. Use of more characters in a password helps to exponentially increase the time and/or resources required to compromise the password.

Satisfies: SRG-OS-000078-GPOS-00046, SRG-OS-000730-GPOS-00190

Check

Verify the pwquality configuration file enforces a minimum 15-character password length with the following command:

$ grep -i minlen /etc/security/pwquality.conf
minlen=15

If "minlen" parameter value is not "15" or higher, is commented out, or is missing, this is a finding.

Fix

Configure Ubuntu 24.04 LTS to enforce a minimum 15-character password length.

Add or modify the "minlen" parameter value to the "/etc/security/pwquality.conf" file:

minlen=15

Ubuntu 24.04 LTS must enforce password complexity by requiring that at least one special character be used.

STIG ID: UBTU-24-400330 | SRG: SRG-OS-000266-GPOS-00101 | Severity: medium | CCI: CCI-004065,CCI-004066 | Vulnerability Id: V-270733

Vulnerability Discussion

Use of a complex password helps to increase the time and resources required to compromise the password. Password complexity or strength is a measure of the effectiveness of a password in resisting attempts at guessing and brute-force attacks.

Password complexity is one factor in determining how long it takes to crack a password. The more complex the password, the greater the number of possible combinations that need to be tested before the password is compromised.

Special characters are those characters that are not alphanumeric. Examples include: ~ ! @ # $ % ^ *.

Satisfies: SRG-OS-000266-GPOS-00101, SRG-OS-000730-GPOS-00190

Check

Determine if the field "ocredit" is set in the "/etc/security/pwquality.conf" file with the following command:

$ grep -i "ocredit" /etc/security/pwquality.conf
ocredit=-1

If the "ocredit" parameter is greater than "-1", is commented out, or is missing, this is a finding.

Fix

Configure Ubuntu 24.04 LTS to enforce password complexity by requiring that at least one special character be used.

Add or update the following line in the "/etc/security/pwquality.conf" file to include the "ocredit=-1" parameter:

ocredit=-1

Ubuntu 24.04 LTS must be configured such that Pluggable Authentication Module (PAM) prohibits the use of cached authentications after one day.

STIG ID: UBTU-24-400340 | SRG: SRG-OS-000383-GPOS-00166 | Severity: low | CCI: CCI-002007 | Vulnerability Id: V-270734

Vulnerability Discussion

If cached authentication information is out-of-date, the validity of the authentication information may be questionable.

Check

Note: If smart card authentication is not being used on the system, this is not applicable.

Verify that PAM prohibits the use of cached authentications after one day with the following command:

$ sudo grep offline_credentials_expiration /etc/sssd/sssd.conf /etc/sssd/conf.d/*.conf
offline_credentials_expiration = 1

If "offline_credentials_expiration" is not set to a value of "1" in "/etc/sssd/sssd.conf" or in a file with a name ending in .conf in the "/etc/sssd/conf.d/" directory, this is a finding.

Fix

Configure PAM to prohibit the use of cached authentications after one day. Add or change the following line in "/etc/sssd/sssd.conf" just below the line "[pam]":

offline_credentials_expiration = 1

Note: It is valid for this configuration to be in a file with a name that ends with ".conf" and does not begin with a "." in the "/etc/sssd/conf.d/" directory instead of the "/etc/sssd/sssd.conf" file.

Ubuntu 24.04 LTS, for PKI-based authentication, SSSD must validate certificates by constructing a certification path (which includes status information) to an accepted trust anchor.

STIG ID: UBTU-24-400360 | SRG: SRG-OS-000066-GPOS-00034 | Severity: medium | CCI: CCI-000185,CCI-004909 | Vulnerability Id: V-270735

Vulnerability Discussion

Without path validation, an informed trust decision by the relying party cannot be made when presented with any certificate not already explicitly trusted.

A trust anchor is an authoritative entity represented via a public key and associated data. It is used in the context of public key infrastructures, X.509 digital certificates, and DNSSEC.

When there is a chain of trust, usually the top entity to be trusted becomes the trust anchor; it can be, for example, a certification authority (CA). A certification path starts with the subject certificate and proceeds through a number of intermediate certificates up to a trusted root certificate, typically issued by a trusted CA.

This requirement verifies that a certification path to an accepted trust anchor is used for certificate validation and that the path includes status information. Path validation is necessary for a relying party to make an informed trust decision when presented with any certificate not already explicitly trusted. Status information for certification paths includes certificate revocation lists or online certificate status protocol responses. Validation of the certificate status information is out of scope for this requirement.

Satisfies: SRG-OS-000066-GPOS-00034, SRG-OS-000775-GPOS-00230

Check

Verify Ubuntu 24.04 LTS, for PKI-based authentication, has valid certificates by constructing a certification path to an accepted trust anchor.

Ensure the pam service is listed under [sssd] with the following command:

$ sudo grep -A 1 '^\[sssd\]' /etc/sssd/sssd.conf
[sssd]
services = nss,pam,ssh

If "pam" is not listed in services, this is a finding.

Additionally, ensure the pam service is set to use pam for smart card authentication in the [pam] section of /etc/sssd/sssd.conf with the following command:

$ sudo grep -A 1 '^\[pam]' /etc/sssd/sssd.conf
[pam]
pam_cert_auth = True

If "pam_cert_auth = True" is not returned, this is a finding.

Ensure "ca" is enabled in "certificate_verification" with the following command:

$ sudo grep certificate_verification /etc/sssd/sssd.conf
certificate_verification = ca_cert,ocsp

If "certificate_verification" is not set to "ca" or the line is commented out, this is a finding.

Fix

Configure Ubuntu 24.04 LTS, for PKI-based authentication, to validate certificates by constructing a certification path to an accepted trust anchor.

Add or update the /etc/sssd/sssd.conf so that the following entries are in the correct sections of the file:

$ sudo vi /etc/sssd/sssd.conf

[sssd]
services = nss,pam,ssh
config_file_version = 2

[pam]
pam_cert_auth = True

[domain/example.com]
ldap_user_certificate = usercertificate;binary
certificate_verification = ca_cert,ocsp
ca_cert = /etc/ssl/certs/ca-certificates.crt

Ubuntu 24.04 LTS must map the authenticated identity to the user or group account for PKI-based authentication.

STIG ID: UBTU-24-400370 | SRG: SRG-OS-000068-GPOS-00036 | Severity: high | CCI: CCI-000187 | Vulnerability Id: V-270736

Vulnerability Discussion

Without mapping the certificate used to authenticate to the user account, the ability to determine the identity of the individual user or group will not be available for forensic analysis.

Check

Verify that authenticated certificates are mapped to the appropriate user group in the "/etc/sssd/sssd.conf" file with the following command:

$ grep -i ldap_user_certificate /etc/sssd/sssd.conf
ldap_user_certificate=userCertificate;binary

Fix

Configure sssd to map authenticated certificates to the appropriate user group by adding the following line to the "/etc/sssd/sssd.conf" file:

ldap_user_certificate=userCertificate;binary

Ubuntu 24.04 LTS, for PKI-based authentication, Privileged Access Management (PAM) must validate certificates by constructing a certification path (which includes status information) to an accepted trust anchor.

STIG ID: UBTU-24-400375 | SRG: SRG-OS-000066-GPOS-00034 | Severity: medium | CCI: CCI-000185,CCI-004909 | Vulnerability Id: V-270737

Vulnerability Discussion

Check

Verify Ubuntu 24.04 LTS, for PKI-based authentication, has valid certificates by constructing a certification path to an accepted trust anchor.

Determine which pkcs11 module is being used via the "use_pkcs11_module" in "/etc/pam_pkcs11/pam_pkcs11.conf" and then ensure "ca" is enabled in "cert_policy" with the following command:

$ sudo grep use_pkcs11_module /etc/pam_pkcs11/pam_pkcs11.conf | awk '/pkcs11_module opensc {/,/}/' /etc/pam_pkcs11/pam_pkcs11.conf | grep cert_policy | grep ca

cert_policy = ca,signature,ocsp_on;

If "cert_policy" is not set to "ca" or the line is commented out, this is a finding.

Fix

Configure Ubuntu 24.04 LTS, for PKI-based authentication, to validate certificates by constructing a certification path to an accepted trust anchor.

Determine which pkcs11 module is being used via the "use_pkcs11_module" in "/etc/pam_pkcs11/pam_pkcs11.conf" and ensure "ca" is enabled in "cert_policy".

Add or update the "cert_policy" to ensure "ca" is enabled:

cert_policy = ca,signature,ocsp_on;

If the system is missing an "/etc/pam_pkcs11/" directory and an "/etc/pam_pkcs11/pam_pkcs11.conf", find an example to copy into place and modify accordingly at "https://manpages.ubuntu.com/manpages/xenial/man8/pam_pkcs11.8.html".

Ubuntu 24.04 LTS for PKI-based authentication, must implement a local cache of revocation data in case of the inability to access revocation information via the network.

STIG ID: UBTU-24-400380 | SRG: SRG-OS-000384-GPOS-00167 | Severity: medium | CCI: CCI-004068 | Vulnerability Id: V-270738

Vulnerability Discussion

Without configuring a local cache of revocation data, there is the potential to allow access to users who are no longer authorized (users with revoked certificates).

Check

Note: If smart card authentication is not being used on the system, this is not applicable.

Verify Ubuntu 24.04 LTS, for PKI-based authentication, uses local revocation data when unable to access it from the network with the following command:

$ grep cert_policy /etc/pam_pkcs11/pam_pkcs11.conf | grep -E -- 'crl_auto|crl_offline'
cert_policy = ca,signature,ocsp_on,crl_auto;

If "cert_policy" is not set to include "crl_auto" or "crl_offline", this is a finding.

Fix

Configure Ubuntu 24.04 LTS, for PKI-based authentication, to use local revocation data when unable to access the network to obtain it remotely.

Add or update the "cert_policy" option in "/etc/pam_pkcs11/pam_pkcs11.conf" to include "crl_auto" or "crl_offline".

cert_policy = ca,signature,ocsp_on, crl_auto;

If the system is missing an "/etc/pam_pkcs11/" directory and an "/etc/pam_pkcs11/pam_pkcs11.conf", find an example to copy into place and modify accordingly at "/usr/share/doc/libpam-pkcs11/examples/pam_pkcs11.conf.example.gz".

Ubuntu 24.04 LTS must encrypt all stored passwords with a FIPS 140-3 approved cryptographic hashing algorithm.

STIG ID: UBTU-24-400400 | SRG: SRG-OS-000120-GPOS-00061 | Severity: medium | CCI: CCI-000803 | Vulnerability Id: V-270739

Vulnerability Discussion

Passwords need to be protected at all times, and encryption is the standard method for protecting passwords. If passwords are not encrypted, they can be plainly read (i.e., clear text) and easily compromised.

Check

Verify the shadow password suite configuration is set to encrypt passwords with a FIPS 140-3 approved cryptographic hashing algorithm with the following command:

$ grep -i ENCRYPT_METHOD /etc/login.defs
ENCRYPT_METHOD SHA512

If "ENCRYPT_METHOD" does not equal SHA512 or greater, this is a finding.

Fix

Configure Ubuntu 24.04 LTS to encrypt all stored passwords.

Edit/modify the following line in the "/etc/login.defs" file and set "ENCRYPT_METHOD" to SHA512:

ENCRYPT_METHOD SHA512

Ubuntu 24.04 LTS must generate audit records for privileged activities, nonlocal maintenance, diagnostic sessions, and other system-level access.

STIG ID: UBTU-24-500010 | SRG: SRG-OS-000392-GPOS-00172 | Severity: medium | CCI: CCI-002884,CCI-000172 | Vulnerability Id: V-270740

Vulnerability Discussion

If events associated with nonlocal administrative access or diagnostic sessions are not logged, a major tool for assessing and investigating attacks would not be available.

This requirement addresses auditing-related issues associated with maintenance tools used specifically for diagnostic and repair actions on organizational information systems.

Nonlocal maintenance and diagnostic activities are those activities conducted by individuals communicating through a network, either an external network (e.g., the internet) or an internal network. Local maintenance and diagnostic activities are those activities carried out by individuals physically present at the information system or information system component and not communicating across a network connection.

This requirement applies to hardware/software diagnostic test equipment or tools. This requirement does not cover hardware/software components that may support information system maintenance, yet are a part of the system, for example, the software implementing "ping," "ls," "ipconfig," or the hardware and software implementing the monitoring port of an Ethernet switch.

Satisfies: SRG-OS-000392-GPOS-00172, SRG-OS-000471-GPOS-00215

Check

Verify Ubuntu 24.04 LTS audits activities performed during nonlocal maintenance and diagnostic sessions with the following command:

$ sudo auditctl -l | grep sudo.log
-w /var/log/sudo.log -p wa -k maintenance

If the command does not return lines that match the example or the lines are commented out, this is a finding.

Note: The "-k" allows for specifying an arbitrary identifier, and the string after it does not need to match the example output above.

Fix

Configure Ubuntu 24.04 LTS to audit activities performed during nonlocal maintenance and diagnostic sessions.

Add or update the following rules in the "/etc/audit/rules.d/stig.rules" file:

-w /var/log/sudo.log -p wa -k maintenance

To reload the rules file, issue the following command:

$ sudo augenrules --load

Ubuntu 24.04 LTS must use strong authenticators in establishing nonlocal maintenance and diagnostic sessions.

STIG ID: UBTU-24-500050 | SRG: SRG-OS-000125-GPOS-00065 | Severity: medium | CCI: CCI-000877 | Vulnerability Id: V-270741

Vulnerability Discussion

Nonlocal maintenance and diagnostic activities are those activities conducted by individuals communicating through a network, either an external network (e.g., the internet) or an internal network. Local maintenance and diagnostic activities are those activities carried out by individuals physically present at the information system or information system component and not communicating across a network connection. Typically, strong authentication requires authenticators that are resistant to replay attacks and employ multifactor authentication. Strong authenticators include, for example, PKI where certificates are stored on a token protected by a password, passphrase, or biometric.

Check

Verify Ubuntu 24.04 LTS is configured to use strong authenticators in the establishment of nonlocal maintenance and diagnostic maintenance with the following command:

$ sudo grep -r ^UsePAM /etc/ssh/sshd_config*
/etc/ssh/sshd_config:UsePAM yes

If "UsePAM" is not set to "yes", conflicting results are returned, the line is commented out, or is missing, this is a finding.

Fix

Configure Ubuntu 24.04 LTS to use strong authentication when establishing nonlocal maintenance and diagnostic sessions.

Add or modify the following line to /etc/ssh/sshd_config:

UsePAM yes

Ubuntu 24.04 LTS must immediately terminate all network connections associated with SSH traffic after a period of inactivity.

STIG ID: UBTU-24-600000 | SRG: SRG-OS-000163-GPOS-00072 | Severity: medium | CCI: CCI-001133 | Vulnerability Id: V-270742

Vulnerability Discussion

Automatic session termination addresses the termination of user-initiated logical sessions in contrast to the termination of network connections that are associated with communications sessions (i.e., network disconnect). A logical session (for local, network, and remote access) is initiated whenever a user (or process acting on behalf of a user) accesses an organizational information system. Such user sessions can be terminated (and thus terminate user access) without terminating network sessions.

Session termination terminates all processes associated with a user's logical session except those processes that are specifically created by the user (i.e., session owner) to continue after the session is terminated.

Conditions or trigger events requiring automatic session termination can include, for example, organization-defined periods of user inactivity, targeted responses to certain types of incidents, and time-of-day restrictions on information system use.

This capability is typically reserved for specific Ubuntu 24.04 LTS functionality where the system owner, data owner, or organization requires additional assurance.

Check

Verify that all network connections associated with SSH traffic automatically terminate after a period of inactivity with the following command:

$ sudo grep -ir ClientAliveCountMax /etc/ssh/sshd_config*
/etc/ssh/sshd_config:ClientAliveCountMax 1

If "ClientAliveCountMax" is not to "1", if conflicting results are returned, is commented out, or is missing, this is a finding.

Fix

Configure Ubuntu 24.04 LTS to automatically terminate inactive SSH sessions after a period of inactivity.

Modify or append the following line in the "/etc/ssh/sshd_config" file, replacing "[Count]" with a value of 1:

ClientAliveCountMax 1

Restart the SSH daemon for the changes to take effect:

$ sudo systemctl restart ssh.service

Ubuntu 24.04 LTS must immediately terminate all network connections associated with SSH traffic at the end of the session or after 10 minutes of inactivity.

STIG ID: UBTU-24-600010 | SRG: SRG-OS-000163-GPOS-00072 | Severity: medium | CCI: CCI-001133 | Vulnerability Id: V-270743

Vulnerability Discussion

Terminating an idle session within a short time period reduces the window of opportunity for unauthorized personnel to take control of a management session enabled on the console or console port that has been left unattended. In addition, quickly terminating an idle session will also free up resources committed by the managed network element.

Terminating network connections associated with communications sessions includes, for example, de-allocating associated TCP/IP address/port pairs at Ubuntu 24.04 LTS level, and de-allocating networking assignments at the application level if multiple application sessions are using a single operating system-level network connection. This does not mean that Ubuntu 24.04 LTS terminates all sessions or network access; it only ends the inactive session and releases the resources associated with that session.

Check

Verify that all network connections associated with SSH traffic are automatically terminated at the end of the session or after 10 minutes of inactivity with the following command:

$ grep -ir ClientAliveInterval /etc/ssh/sshd_config*
/etc/ssh/sshd_config:ClientAliveInterval 600

If "ClientAliveInterval" does not exist, is not set to a value of "600" or less in "/etc/ssh/sshd_config", if conflicting results are returned, is commented out, or is missing, this is a finding.

Fix

Configure Ubuntu 24.04 LTS to automatically terminate all network connections associated with SSH traffic at the end of a session or after a 10-minute period of inactivity.

In the file /etc/ssh/sshd_config set ClientAliveInterval to a value of "600" or less:

ClientAliveInterval 600

Restart the SSH daemon for the changes to take effect:

$ sudo systemctl restart sshd.service

Ubuntu 24.04 LTS must implement NIST FIPS-validated cryptography to protect classified information and for the following: To provision digital signatures, to generate cryptographic hashes, and to protect unclassified information requiring confidentiality and cryptographic protection in accordance with applicable federal laws, Executive Orders, directives, policies, regulations, and standards.

STIG ID: UBTU-24-600030 | SRG: SRG-OS-000478-GPOS-00223 | Severity: high | CCI: CCI-002450 | Vulnerability Id: V-270744

Vulnerability Discussion

Use of weak or untested encryption algorithms undermines the purposes of utilizing encryption to protect data. Ubuntu 24.04 LTS must implement cryptographic modules adhering to the higher standards approved by the federal government since this provides assurance they have been tested and validated.

Satisfies: SRG-OS-000478-GPOS-00223, SRG-OS-000396-GPOS-00176

Check

Verify the system is configured to run in FIPS mode with the following command:

$ grep -i 1 /proc/sys/crypto/fips_enabled
1

If a value of "1" is not returned, this is a finding.

Fix

Configure the system to run in FIPS mode. Add "fips=1" to the kernel parameter during Ubuntu 24.04 LTSs install.

Enabling a FIPS mode on a pre-existing system involves a number of modifications to Ubuntu 24.04 LTS. Refer to the Ubuntu Pro security certification documentation for instructions.

A subscription to the "Ubuntu Pro" plan is required to obtain the FIPS Kernel cryptographic modules and enable FIPS.

Note: Ubuntu Pro security certification instructions can be found at: https://ubuntu.com/security/certifications/docs/fips-enablement

The basic steps use the following commands:

$ sudo pro attach <token>
$ sudo pro enable fips-updates

Ubuntu 24.04 LTS must use DOD PKI-established certificate authorities (CAs) for verification of the establishment of protected sessions.

STIG ID: UBTU-24-600060 | SRG: SRG-OS-000403-GPOS-00182 | Severity: medium | CCI: CCI-002470 | Vulnerability Id: V-270745

Vulnerability Discussion

Untrusted CAs can issue certificates, but they may be issued by organizations or individuals that seek to compromise DOD systems or by organizations with insufficient security controls. If the CA used for verifying the certificate is not a DOD-approved CA, trust of this CA has not been established.

The DOD will only accept PKI-certificates obtained from a DOD-approved internal or external certificate authority. Reliance on CAs for the establishment of secure sessions includes, for example, the use of SSL/TLS certificates.

Check

Verify the directory containing the root certificates for Ubuntu 24.04 LTS contains certificate files for DOD PKI-established CAs by iterating over all files in the "/etc/ssl/certs" directory and checking if, at least one, has the subject matching "DOD ROOT CA".

$ grep -ir DOD /etc/ssl/certs
DOD_PKE_CA_chain.pem

If no root certificate is found, this is a finding.

Fix

Configure Ubuntu 24.04 LTS to use of DOD PKI-established CAs for verification of the establishment of protected sessions.

Edit the "/etc/ca-certificates.conf" file, adding the character "!" to the beginning of all uncommented lines that do not start with the "!" character with the following command:

$ sudo sed -i -E 's/^([^!#]+)/!\1/' /etc/ca-certificates.conf

Add at least one CA to the "/usr/local/share/ca-certificates" directory in the PEM format.

Update the "/etc/ssl/certs" directory with the following command:

$ sudo update-ca-certificates

Ubuntu 24.04 LTS must disable kernel core dumps.

STIG ID: UBTU-24-600070 | SRG: SRG-OS-000184-GPOS-00078 | Severity: medium | CCI: CCI-001190 | Vulnerability Id: V-270746

Vulnerability Discussion

Kernel core dumps may contain the full contents of system memory at the time of the crash. Kernel core dumps may consume a considerable amount of disk space and may result in denial of service by exhausting the available space on the target file system partition.

Check

Verify that kernel core dumps are disabled unless needed with the following command:

$ systemctl is-active kdump.service
inactive

If the "kdump" service is active, ask the system administrator (SA) if the use of the service is required and documented with the information system security officer (ISSO).

If the service is active and is not documented, this is a finding.

Fix

If kernel core dumps are not required, disable the "kdump" service with the following command:

$ sudo systemctl disable kdump.service

If kernel core dumps are required, document the need with the ISSO.

Ubuntu 24.04 LTS handling data requiring "data at rest" protections must employ cryptographic mechanisms to prevent unauthorized disclosure and modification of the information at rest.

STIG ID: UBTU-24-600090 | SRG: SRG-OS-000185-GPOS-00079 | Severity: medium | CCI: CCI-001199,CCI-002475,CCI-002476,CCI-004910 | Vulnerability Id: V-270747

Vulnerability Discussion

Information at rest refers to the state of information when it is located on a secondary storage device (e.g., disk drive and tape drive, when used for backups) within an operating system.

This requirement addresses protection of user-generated data, as well as operating system-specific configuration data. Organizations may choose to employ different mechanisms to achieve confidentiality and integrity protections, as appropriate, in accordance with the security category and/or classification of the information.

Satisfies: SRG-OS-000185-GPOS-00079, SRG-OS-000404-GPOS-00183, SRG-OS-000405-GPOS-00184, SRG-OS-000780-GPOS-00240

Check

Note: If there is a documented and approved mission requirement for data-at-rest to not be encrypted, this requirement is not applicable.

Verify Ubuntu 24.04 LTS prevents unauthorized disclosure or modification of all information requiring at-rest protection by using disk encryption.

Determine the partition layout for the system with the following command:

$ sudo fdisk -l
(..)
Disk /dev/vda: 15 GiB, 16106127360 bytes, 31457280 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: gpt
Disk identifier: 83298450-B4E3-4B19-A9E4-7DF147A5FEFB

Device Start End Sectors Size Type
/dev/vda1 2048 4095 2048 1M BIOS boot
/dev/vda2 4096 2101247 2097152 1G Linux filesystem
/dev/vda3 2101248 31455231 29353984 14G Linux filesystem
(...)

Verify the system partitions are all encrypted with the following command:

$ more /etc/crypttab

Every persistent disk partition present must have an entry in the file.

If any partitions other than the boot partition or pseudo file systems (such as /proc or /sys) are not listed, this is a finding.

Fix

To encrypt an entire partition, dedicate a partition for encryption in the partition layout.

Note: Encrypting a partition in an already-installed system is more difficult because it will need to be resized and existing partitions changed.

Ubuntu 24.04 LTS must ensure only users who need access to security functions are part of sudo group.

STIG ID: UBTU-24-600130 | SRG: SRG-OS-000134-GPOS-00068 | Severity: high | CCI: CCI-001084 | Vulnerability Id: V-270748

Vulnerability Discussion

An isolation boundary provides access control and protects the integrity of the hardware, software, and firmware that perform security functions.

Security functions are the hardware, software, and/or firmware of the information system responsible for enforcing the system security policy and supporting the isolation of code and data on which the protection is based. Operating systems implement code separation (i.e., separation of security functions from nonsecurity functions) in a number of ways, including through the provision of security kernels via processor rings or processor modes. For nonkernel code, security function isolation is often achieved through file system protections that serve to protect the code on disk and address space protections that protect executing code.

Developers and implementers can increase the assurance in security functions by employing well-defined security policy models; structured, disciplined, and rigorous hardware and software development techniques; and sound system/security engineering principles. Implementation may include isolation of memory space and libraries.

Ubuntu 24.04 LTS restricts access to security functions through the use of access control mechanisms and by implementing least privilege capabilities.

Check

Verify the sudo group has only members who require access to security functions with the following command:

$ grep sudo /etc/group
sudo:x:27:foo

If the sudo group contains users not needing access to security functions, this is a finding.

Fix

Configure the sudo group with only members requiring access to security functions.

To remove a user from the sudo group, run:

$ sudo gpasswd -d <username> sudo

Ubuntu 24.04 LTS must restrict access to the kernel message buffer.

STIG ID: UBTU-24-600140 | SRG: SRG-OS-000138-GPOS-00069 | Severity: low | CCI: CCI-001090 | Vulnerability Id: V-270749

Vulnerability Discussion

Restricting access to the kernel message buffer limits access only to root. This prevents attackers from gaining additional system information as a nonprivileged user.

Check

Verify Ubuntu 24.04 LTS is configured to restrict access to the kernel message buffer with the following command:

$ sysctl kernel.dmesg_restrict
kernel.dmesg_restrict = 1

If "kernel.dmesg_restrict" is not set to "1" or is missing, this is a finding.

Verify there are no configurations that enable the kernel dmesg function:

$ sudo grep -r kernel.dmesg_restrict /run/sysctl.d/* /etc/sysctl.d/* /usr/local/lib/sysctl.d/* /usr/lib/sysctl.d/* /lib/sysctl.d/* /etc/sysctl.conf 2> /dev/null
/etc/sysctl.d/10-kernel-hardening.conf:kernel.dmesg_restrict = 1

If any instance of "kernel.dmesg_restrict" is uncommented and set to "0", or if conflicting results are returned, this is a finding.

Fix

Configure Ubuntu 24.04 LTS to restrict access to the kernel message buffer.

Set the system to the required kernel parameter by adding or modifying the following line in /etc/sysctl.conf or a config file in the /etc/sysctl.d/ directory:

kernel.dmesg_restrict = 1

Remove any configurations that conflict with the above from the following locations:
/run/sysctl.d/
/etc/sysctl.d/
/usr/local/lib/sysctl.d/
/usr/lib/sysctl.d/
/lib/sysctl.d/
/etc/sysctl.conf

Reload settings from all system configuration files with the following command:

$ sudo sysctl --system

Ubuntu 24.04 LTS must set a sticky bit on all public directories to prevent unauthorized and unintended information transferred via shared system resources.

STIG ID: UBTU-24-600150 | SRG: SRG-OS-000138-GPOS-00069 | Severity: medium | CCI: CCI-001090 | Vulnerability Id: V-270750

Vulnerability Discussion

Preventing unauthorized information transfers mitigates the risk of information, including encrypted representations of information, produced by the actions of prior users/roles (or the actions of processes acting on behalf of prior users/roles) from being available to any current users/roles (or current processes) that obtain access to shared system resources (e.g., registers, main memory, hard disks) after those resources have been released back to information systems. The control of information in shared resources is also commonly referred to as object reuse and residual information protection.

This requirement generally applies to the design of an information technology product, but it can also apply to the configuration of particular information system components that are, or use, such products. This can be verified by acceptance/validation processes in DOD or other government agencies.

There may be shared resources with configurable protections (e.g., files in storage) that may be assessed on specific information system components.

Check

Verify all public (world-writeable) directories have the public sticky bit set with the following command:

$ sudo find / -type d -perm -002 ! -perm -1000

If any world-writable directories are found missing the sticky bit, this is a finding.

Fix

Configure all public directories to have the sticky bit set to prevent unauthorized and unintended information transferred via shared system resources.

Set the sticky bit on all public directories using the following command, replacing "[Public Directory]" with any directory path missing the sticky bit:

$ sudo chmod +t [Public Directory]

Ubuntu 24.04 LTS must compare internal information system clocks at least every 24 hours with an authoritative time server.

STIG ID: UBTU-24-600160 | SRG: SRG-OS-000785-GPOS-00250 | Severity: low | CCI: CCI-004922,CCI-004923 | Vulnerability Id: V-270751

Vulnerability Discussion

Inaccurate time stamps make it more difficult to correlate events and can lead to an inaccurate analysis. Determining the correct time a particular event occurred on a system is critical when conducting forensic analysis and investigating system events. Sources outside the configured acceptable allowance (drift) may be inaccurate.

Synchronizing internal information system clocks provides uniformity of time stamps for information systems with multiple system clocks and systems connected over a network.

Organizations must consider endpoints that may not have regular access to the authoritative time server (e.g., mobile, teleworking, and tactical endpoints).

Satisfies: SRG-OS-000785-GPOS-00250, SRG-OS-000355-GPOS-00143

Check

Note: If the system is not networked, this requirement is not applicable.

Verify Ubuntu 24.04 LTS is configured to compare the system clock at least every 24 hours to an authoritative time source with the following command:

$ sudo grep -ir maxpoll /etc/chrony*
server [source] iburst maxpoll 16

If the parameter "server" is not set, is not set to an authoritative DOD time source, or is commented out, this is a finding.

If the "maxpoll" option is set to a number greater than 16, the line is commented out, or is missing, this is a finding.

Fix

To configure the system clock to compare to the authoritative time source at least every 24 hours, edit the "/etc/chrony/chrony.conf" file. Add or correct the following lines, by replacing "[source]" in the following line with an authoritative time source:

server [source] iburst maxpoll 16

If the "chrony" service was running and the value of "maxpoll" or "server" was updated, the service must be restarted using the following command:

$ sudo systemctl restart chrony.service

Ubuntu 24.04 LTS must synchronize internal information system clocks to the authoritative time source when the time difference is greater than one second.

STIG ID: UBTU-24-600180 | SRG: SRG-OS-000356-GPOS-00144 | Severity: low | CCI: CCI-004926 | Vulnerability Id: V-270752

Vulnerability Discussion

Inaccurate time stamps make it more difficult to correlate events and can lead to an inaccurate analysis. Determining the correct time a particular event occurred on a system is critical when conducting forensic analysis and investigating system events.

Synchronizing internal information system clocks provides uniformity of time stamps for information systems with multiple system clocks and systems connected over a network. Organizations must consider setting time periods for different types of systems (e.g., financial, legal, or mission-critical systems).

Organizations must also consider endpoints that may not have regular access to the authoritative time server (e.g., mobile, teleworking, and tactical endpoints). This requirement is related to the comparison done every 24 hours in SRG-OS-000355 because a comparison must be done to determine the time difference.

Check

Verify Ubuntu 24.04 LTS synchronizes internal system clocks to the authoritative time source when the time difference is greater than one second.

Check the value of "makestep" with the following command:

$ grep makestep /etc/chrony/chrony.conf
makestep 1 -1

If the makestep option is not set to "1 -1", is commented out, or is missing, this is a finding.

Fix

Configure chrony to synchronize the internal system clocks to the authoritative source when the time difference is greater than one second by doing the following:

Edit the "/etc/chrony/chrony.conf" file and add:

makestep 1 -1

Restart the chrony service:

$ sudo systemctl restart chrony.service

Ubuntu 24.04 LTS must be configured to use TCP syncookies.

STIG ID: UBTU-24-600190 | SRG: SRG-OS-000142-GPOS-00071 | Severity: medium | CCI: CCI-001095 | Vulnerability Id: V-270753

Vulnerability Discussion

Denial of service (DoS) occurs when a resource is not available for legitimate users, resulting in the organization not being able to accomplish its mission or causing it to operate at degraded capacity.

Managing excess capacity ensures sufficient capacity is available to counter flooding attacks. Employing increased capacity and service redundancy may reduce the susceptibility to some DoS attacks. Managing excess capacity may include, for example, establishing selected usage priorities, quotas, or partitioning.

Check

Verify Ubuntu 24.04 LTS is configured to use TCP syncookies with the following command:

$ sysctl net.ipv4.tcp_syncookies
net.ipv4.tcp_syncookies = 1

If the value is not "1", this is a finding.

Check the saved value of TCP syncookies with the following command:

$ sudo grep -ir net.ipv4.tcp_syncookies /etc/sysctl.d/*.conf /run/sysctl.d/*.conf /usr/local/lib/sysctl.d/*.conf /usr/lib/sysctl.d/*.conf /lib/sysctl.d/*.conf /etc/sysctl.conf 2> /dev/null
/etc/sysctl.d/99-sysctl.conf:net.ipv4.tcp_syncookies=1
/etc/sysctl.conf:net.ipv4.tcp_syncookies=1

If the "net.ipv4.tcp_syncookies" option is not set to "1", is commented out, or is missing, this is a finding.

Fix

Configure Ubuntu 24.04 LTS to use TCP syncookies with the following command:

$ sudo sysctl -w net.ipv4.tcp_syncookies=1

If "1" is not the system's default value, add or update the following line in "/etc/sysctl.conf":

net.ipv4.tcp_syncookies = 1

Ubuntu 24.04 LTS must configure the uncomplicated firewall to rate-limit impacted network interfaces.

STIG ID: UBTU-24-600200 | SRG: SRG-OS-000420-GPOS-00186 | Severity: medium | CCI: CCI-002385 | Vulnerability Id: V-270754

Vulnerability Discussion

Denial of service (DoS) occurs when a resource is not available for legitimate users, resulting in the organization not being able to accomplish its mission or causing it to operate at degraded capacity.

This requirement addresses the configuration of Ubuntu 24.04 LTS to mitigate the impact of DoS attacks that have occurred or are ongoing on system availability. For each system, known and potential DoS attacks must be identified and solutions for each type implemented. A variety of technologies exist to limit or, in some cases, eliminate the effects of DoS attacks (e.g., limiting processes or establishing memory partitions). Employing increased capacity and bandwidth, combined with service redundancy, may reduce the susceptibility to some DoS attacks.

Check

Verify an application firewall is configured to rate limit any connection to the system.

Check all the services listening to the ports with the following command:

$ ss -l46ut
Netid State Recv-Q Send-Q Local Address:Port Peer Address:Port Process
tcp LISTEN 0 511 *:http *:*
tcp LISTEN 0 128 [::]:ssh [::]:*
tcp LISTEN 0 128 [::]:ipp [::]:*
tcp LISTEN 0 128 [::]:smtp [::]:*

For each entry, verify the Uncomplicated Firewall (ufw) is configured to rate limit the service ports with the following command:

$ sudo ufw status
Status: active

To Action From
-- ------ ----
80/tcp LIMIT Anywhere
25/tcp LIMIT Anywhere
Anywhere DENY 177.60.7.4
443 LIMIT Anywhere
22/tcp LIMIT Anywhere
80/tcp (v6) LIMIT Anywhere
25/tcp (v6) LIMIT Anywhere
22/tcp (v6) LIMIT Anywhere (v6)

25 DENY OUT Anywhere
25 (v6) DENY OUT Anywhere (v6)

If any port with a state of "LISTEN" that does not have an action of "DENY", is not marked with the "LIMIT" action, this is a finding. If the Status is set to anything other than "active" this is a finding.

Fix

Configure the application firewall to protect against or limit the effects of DoS attacks by ensuring Ubuntu 24.04 LTS is implementing rate-limiting measures on impacted network interfaces.

To change the Status of ufw to "active" use the following command:
$ sudo ufw enable

Check all the services listening to the ports with the following command:

$ sudo ss -l46ut
Netid State Recv-Q Send-Q Local Address:Port Peer Address:Port Process
tcp LISTEN 0 128 [::]:ssh [::]:*

For each service with a port listening to connections, run the following command, replacing "[service]" with the service that needs to be rate limited.

$ sudo ufw limit [service]

Rate-limiting can also be done on an interface. An example of adding a rate-limit on the eth0 interface follows:

$ sudo ufw limit in on eth0

Ubuntu 24.04 LTS must disable all wireless network adapters.

STIG ID: UBTU-24-600230 | SRG: SRG-OS-000481-GPOS-00481 | Severity: medium | CCI: CCI-002418 | Vulnerability Id: V-270755

Vulnerability Discussion

Without protection of communications with wireless peripherals, confidentiality and integrity may be compromised because unprotected communications can be intercepted and either read, altered, or used to compromise Ubuntu 24.04 LTS.

This requirement applies to wireless peripheral technologies (e.g., wireless mice, keyboards, displays, etc.) used with an operating system. Wireless peripherals (e.g., Wi-Fi/Bluetooth/IR Keyboards, Mice, and Pointing Devices and Near Field Communications [NFC]) present a unique challenge by creating an open, unsecured port on a computer. Wireless peripherals must meet DOD requirements for wireless data transmission and be approved for use by the approving authority (AO). Even though some wireless peripherals, such as mice and pointing devices, do not ordinarily carry information that need to be protected, modification of communications with these wireless peripherals may be used to compromise Ubuntu 24.04 LTS. Communication paths outside the physical protection of a controlled boundary are exposed to the possibility of interception and modification.

Protecting the confidentiality and integrity of communications with wireless peripherals can be accomplished by physical means (e.g., employing physical barriers to wireless radio frequencies) or by logical means (e.g., employing cryptographic techniques). If physical means of protection are employed, then logical means (cryptography) do not have to be employed, and vice versa. If the wireless peripheral is only passing telemetry data, encryption of the data may not be required.

Check

Note: This requirement is not applicable for systems that do not have physical wireless network radios.

Verify there are no wireless interfaces configured on the system with the following command:

$ ls -L -d /sys/class/net/*/wireless | xargs dirname | xargs basename

If a wireless interface is configured and has not been documented and approved by the information system security officer (ISSO), this is a finding.

Fix

List all the wireless interfaces with the following command:

$ ls -L -d /sys/class/net/*/wireless | xargs dirname | xargs basename

For each interface, configure the system to disable wireless network interfaces with the following command:

$ sudo ifdown <interface name>

For each interface listed, find their respective module with the following command:

$ basename $(readlink -f /sys/class/net/<interface name>/device/driver)

where <interface name> must be substituted by the actual interface name.

Create a file in the "/etc/modprobe.d" directory and for each module, add the following line:

install <module name> /bin/true

For each module from the system, execute the following command to remove it:

$ sudo modprobe -r <module name>

Ubuntu 24.04 LTS must generate error messages that provide information necessary for corrective actions without revealing information that could be exploited by adversaries.

STIG ID: UBTU-24-700010 | SRG: SRG-OS-000205-GPOS-00083 | Severity: medium | CCI: CCI-001312 | Vulnerability Id: V-270756

Vulnerability Discussion

Any operating system providing too much information in error messages risks compromising the data and security of the structure, and content of error messages needs to be carefully considered by the organization.

Organizations carefully consider the structure/content of error messages. The extent to which information systems are able to identify and handle error conditions is guided by organizational policy and operational requirements. Information that could be exploited by adversaries includes, for example, erroneous logon attempts with passwords entered by mistake as the username, mission/business information that can be derived from (if not stated explicitly by) information recorded, and personal information, such as account numbers, social security numbers, and credit card numbers.

The /var/log/btmp, /var/log/wtmp, and /var/log/lastlog files have group write and global read permissions to allow for the lastlog function to perform. Limiting the permissions beyond this configuration will result in the failure of functions that rely on the lastlog database.

Check

Verify Ubuntu 24.04 LTS has all system log files under the /var/log directory with a permission set to "640" or less permissive with the following command:

Note: The btmp, wtmp, and lastlog files are excluded. Refer to the Discussion for details.

$ sudo find /var/log -perm /137 ! -name '*[bw]tmp' ! -name '*lastlog' -type f -exec stat -c "%n %a" {} \;

If the command displays any output, this is a finding.

Fix

Configure Ubuntu 24.04 LTS to set permissions of all log files under the /var/log directory to "640" or more restricted by using the following command:

Note: The btmp, wtmp, and lastlog files are excluded. Refer to the Discussion for details.

$ sudo find /var/log -perm /137 ! -name '*[bw]tmp' ! -name '*lastlog' -type f -exec chmod 640 '{}' \;

Ubuntu 24.04 LTS must generate system journal entries without revealing information that could be exploited by adversaries.

STIG ID: UBTU-24-700020 | SRG: SRG-OS-000205-GPOS-00083 | Severity: medium | CCI: CCI-001312 | Vulnerability Id: V-270757

Vulnerability Discussion

Any operating system providing too much information in error messages risks compromising the data and security of the structure, and content of error messages must be carefully considered by the organization.

Organizations carefully consider the structure/content of error messages. The extent to which information systems are able to identify and handle error conditions is guided by organizational policy and operational requirements. Information that could be exploited by adversaries includes, for example, erroneous logon attempts with passwords entered by mistake as the username, mission/business information that can be derived from (if not stated explicitly by) information recorded, and personal information, such as account numbers, social security numbers, and credit card numbers.

Check

Verify the /run/log/journal and /var/log/journal directories have permissions set to "2640" or less permissive with the following command:

$ sudo find /run/log/journal /var/log/journal -type d -exec stat -c "%n %a" {} \;
/run/log/journal 2640
/var/log/journal 2640
/var/log/journal/d5745ad455d34fb8b6f78be37c1fcd3e 2640

If any output returned has a permission set greater than 2640, this is a finding.

Verify all files in the /run/log/journal and /var/log/journal directories have permissions set to "640" or less permissive with the following command:

$ sudo find /run/log/journal /var/log/journal -type f -exec stat -c "%n %a" {} \;
/var/log/journal/d5745ad455d34fb8b6f78be37c1fcd3e/system.journal 640
/var/log/journal/d5745ad455d34fb8b6f78be37c1fcd3e/user-1000@0005f97cd4a8c9b5a.journal~ 640
/var/log/journal/d5745ad455d34fb8b6f78be37c1fcd3e/system@0005f97cd2a1e0a7-d58b848af46813a4.journal~ 640
/var/log/journal/d5745ad455d34fb8b6f78be37c1fcd3e/system@0005f97cb900e501-55ea053b7f75ae1c.journal~ 640
/var/log/journal/d5745ad455d34fb8b6f78be37c1fcd3e/user-1000.journal 640

If any output returned has a permission set greater than "640", this is a finding.

Fix

Configure the system to set the appropriate permissions to the files and directories used by the systemd journal:

$ sudo nano /usr/lib/tmpfiles.d/systemd.conf

Edit the following lines of the configuration file:

z /run/log/journal 2640 root systemd-journal - -
Z /run/log/journal/%m ~2640 root systemd-journal - -
z /var/log/journal 2640 root systemd-journal - -
z /var/log/journal/%m 2640 root systemd-journal - -
z /var/log/journal/%m/system.journal 0640 root systemd-journal - -

Note: The system must be restarted for these settings to take effect.

Ubuntu 24.04 LTS must be configured so that the "journalctl" command is not accessible by unauthorized users.

STIG ID: UBTU-24-700030 | SRG: SRG-OS-000205-GPOS-00083 | Severity: medium | CCI: CCI-001312 | Vulnerability Id: V-270758

Vulnerability Discussion

Check

Verify the journalctl command has a permission set of "740" with the following command:

$ sudo find /usr/bin/journalctl -exec stat -c "%n %a" {} \;
/usr/bin/journalctl 740

If journalctl is not set to "740", this is a finding

Fix

Configure journalctl to have a permission set of "740":

$ sudo chmod 740 /usr/bin/journalctl

Ubuntu 24.04 LTS must be configured so that the "journalctl" command is owned by "root".

STIG ID: UBTU-24-700040 | SRG: SRG-OS-000206-GPOS-00084 | Severity: medium | CCI: CCI-001314 | Vulnerability Id: V-270759

Vulnerability Discussion

Only authorized personnel are to be made aware of errors and the details of the errors. Error messages are an indicator of an organization's operational state or can identify Ubuntu 24.04 LTS or platform. Additionally, Personally Identifiable Information (PII) and operational information must not be revealed through error messages to unauthorized personnel or their designated representatives.

The structure and content of error messages must be carefully considered by the organization and development team. The extent to which the information system is able to identify and handle error conditions is guided by organizational policy and operational requirements.

Check

Verify the journalctl command is owned by "root" with the following command:

$ sudo find /usr/bin/journalctl -exec stat -c "%n %U" {} \;
/usr/bin/journalctl root

If journalctl is not owned by "root", this is a finding.

Fix

Configure journalctl to be owned by "root":

$ sudo chown root /usr/bin/journalctl

Ubuntu 24.04 LTS must be configured so that the "journalctl" command is group-owned by "root".

STIG ID: UBTU-24-700050 | SRG: SRG-OS-000206-GPOS-00084 | Severity: medium | CCI: CCI-001314 | Vulnerability Id: V-270760

Vulnerability Discussion

Check

Verify the journalctl command is group-owned by "root" with the following command:

$ sudo find /usr/bin/journalctl -exec stat -c "%n %G" {} \;
/usr/bin/journalctl root

If journalctl is not group-owned by "root", this is a finding

Fix

Configure journalctl to be group-owned by "root":

$ sudo chown :root /usr/bin/journalctl

Ubuntu 24.04 LTS must configure the directories used by the system journal to be group-owned by "systemd-journal".

STIG ID: UBTU-24-700060 | SRG: SRG-OS-000206-GPOS-00084 | Severity: medium | CCI: CCI-001314 | Vulnerability Id: V-270761

Vulnerability Discussion

Check

Verify the /run/log/journal and /var/log/journal directories are group-owned by "systemd-journal" with the following command:

$ sudo find /run/log/journal /var/log/journal -type d -exec stat -c "%n %G" {} \;
/run/log/journal systemd-journal
/var/log/journal systemd-journal
/var/log/journal/d5745ad455d34fb8b6f78be37c1fcd3e systemd-journal

If any output returned is not group-owned by "systemd-journal", this is a finding.

Fix

Configure the system to set the appropriate group-ownership to the directories used by the systemd journal:

$ sudo nano /usr/lib/tmpfiles.d/systemd.conf

Edit the following lines of the configuration file:

z /run/log/journal 2640 root systemd-journal - -
z /var/log/journal 2640 root systemd-journal - -

Note: The system must be restarted for these settings to take effect.

Ubuntu 24.04 LTS must configure the files used by the system journal to be group-owned by "systemd-journal".

STIG ID: UBTU-24-700070 | SRG: SRG-OS-000206-GPOS-00084 | Severity: medium | CCI: CCI-001314 | Vulnerability Id: V-270762

Vulnerability Discussion

Check

Verify the /run/log/journal and /var/log/journal files are group-owned by "systemd-journal" with the following command:

$ sudo find /run/log/journal /var/log/journal -type f -exec stat -c "%n %G" {} \;
/var/log/journal/d5745ad455d34fb8b6f78be37c1fcd3e/system.journal systemd-journal
/var/log/journal/d5745ad455d34fb8b6f78be37c1fcd3e/user-1000@0005f97cd4a8c9b5-f088232c3718485a.journal~ systemd-journal
/var/log/journal/d5745ad455d34fb8b6f78be37c1fcd3e/system@0005f97cd2a1e0a7-d58b848af46813a4.journal~ systemd-journal
/var/log/journal/d5745ad455d34fb8b6f78be37c1fcd3e/system@0005f97cb900e501-55ea053b7f75ae1c.journal~ systemd-journal
/var/log/journal/d5745ad455d34fb8b6f78be37c1fcd3e/user-1000.journal systemd-journal

If any output returned is not group-owned by "systemd-journal", this is a finding.

Fix

Configure the system to set the appropriate group-ownership to the files used by the systemd journal:

Z /run/log/journal/%m ~2640 root systemd-journal - -
z /var/log/journal/%m 2640 root systemd-journal - -
z /var/log/journal/%m/system.journal 0640 root systemd-journal - -

Note: The system must be restarted for these settings to take effect.

Ubuntu 24.04 LTS must configure the directories used by the system journal to be owned by "root".

STIG ID: UBTU-24-700080 | SRG: SRG-OS-000206-GPOS-00084 | Severity: medium | CCI: CCI-001314 | Vulnerability Id: V-270763

Vulnerability Discussion

Check

Verify the /run/log/journal and /var/log/journal directories are owned by "root" with the following command:

$ sudo find /run/log/journal /var/log/journal -type d -exec stat -c "%n %U" {} \;
/run/log/journal root
/var/log/journal root
/var/log/journal/d5745ad455d34fb8b6f78be37c1fcd3e root

If any output returned is not owned by "root", this is a finding.

Fix

Configure the system to set the appropriate ownership to the directories used by the systemd journal:

$ sudo nano /usr/lib/tmpfiles.d/systemd.conf

Edit the following lines of the configuration file:

z /run/log/journal 2640 root systemd-journal - -
z /var/log/journal 2640 root systemd-journal - -

Note: The system must be restarted for these settings to take effect.

Ubuntu 24.04 LTS must configure the files used by the system journal to be owned by "root"

STIG ID: UBTU-24-700090 | SRG: SRG-OS-000206-GPOS-00084 | Severity: medium | CCI: CCI-001314 | Vulnerability Id: V-270764

Vulnerability Discussion

Check

Verify the /run/log/journal and /var/log/journal files are owned by "root" with the following command:

$ sudo find /run/log/journal /var/log/journal -type f -exec stat -c "%n %U" {} \;
/var/log/journal/d5745ad455d34fb8b6f78be37c1fcd3e/system.journal root
/var/log/journal/d5745ad455d34fb8b6f78be37c1fcd3e/user-1000@0005f97cd4a8c9b5-f088232c3718485a.journal~ root
/var/log/journal/d5745ad455d34fb8b6f78be37c1fcd3e/system@0005f97cd2a1e0a7-d58b848af46813a4.journal~ root
/var/log/journal/d5745ad455d34fb8b6f78be37c1fcd3e/system@0005f97cb900e501-55ea053b7f75ae1c.journal~ root
/var/log/journal/d5745ad455d34fb8b6f78be37c1fcd3e/user-1000.journal root

If any output returned is not owned by "root", this is a finding.

Fix

Configure the system to set the appropriate ownership to the files used by the systemd journal:

$ sudo nano /usr/lib/tmpfiles.d/systemd.conf

Edit the following lines of the configuration file:

Z /run/log/journal/%m ~2640 root systemd-journal - -
z /var/log/journal/%m 2640 root systemd-journal - -
z /var/log/journal/%m/system.journal 0640 root systemd-journal - -

Note: The system must be restarted for these settings to take effect.

Ubuntu 24.04 LTS must configure the /var/log directory to be group-owned by syslog.

STIG ID: UBTU-24-700100 | SRG: SRG-OS-000206-GPOS-00084 | Severity: medium | CCI: CCI-001314 | Vulnerability Id: V-270765

Vulnerability Discussion

Check

Verify that Ubuntu 24.04 LTS configures the /var/log directory to be group-owned by "syslog" with the following command:

$ stat -c "%n %G" /var/log
/var/log syslog

If the "/var/log" directory is not group-owned by syslog, this is a finding.

Fix

Configure Ubuntu 24.04 LTS to have syslog group-own the /var/log directory with the following command:

$ sudo chgrp syslog /var/log

Ubuntu 24.04 LTS must configure the /var/log directory to be owned by root.

STIG ID: UBTU-24-700110 | SRG: SRG-OS-000206-GPOS-00084 | Severity: medium | CCI: CCI-001314 | Vulnerability Id: V-270766

Vulnerability Discussion

Check

Verify Ubuntu 24.04 LTS configures the /var/log directory to be owned by "root" with the following command:

$ stat -c "%n %U" /var/log
/var/log root

If the "/var/log" directory is not owned by root, this is a finding.

Fix

Configure Ubuntu 24.04 LTS to have root own the /var/log directory by running the following command:

$ sudo chown root /var/log

Ubuntu 24.04 LTS must configure the /var/log directory to have mode "0755" or less permissive.

STIG ID: UBTU-24-700120 | SRG: SRG-OS-000206-GPOS-00084 | Severity: medium | CCI: CCI-001314 | Vulnerability Id: V-270767

Vulnerability Discussion

Only authorized personnel are to be made aware of errors and the details of the errors. Error messages are an indicator of an organization's operational state or can identify Ubuntu 24.04 LTS or platform. Additionally, personally identifiable information (PII) and operational information must not be revealed through error messages to unauthorized personnel or their designated representatives.

The structure and content of error messages must be carefully considered by the organization and development team. The extent to which the information system is able to identify and handle error conditions is guided by organizational policy and operational requirements.

Check

Note: If rsyslog is active and enabled on Ubuntu 24.04 LTS, this requirement is not applicable.

Verify Ubuntu 24.04 LTS configures the /var/log directory with a mode of "755" or less permissive with the following command:

$ stat -c "%n %a" /var/log
/var/log 755

If a value of "755" or less permissive is not returned, this is a finding.

Fix

Configure Ubuntu 24.04 LTS to have permissions of "0755" for the /var/log directory by running the following command:

$ sudo chmod 0755 /var/log

Ubuntu 24.04 LTS must configure the /var/log/syslog file to be group-owned by adm.

STIG ID: UBTU-24-700130 | SRG: SRG-OS-000206-GPOS-00084 | Severity: medium | CCI: CCI-001314 | Vulnerability Id: V-270768

Vulnerability Discussion

Check

Verify that Ubuntu 24.04 LTS configures the /var/log/syslog file to be group-owned by "adm" with the following command:

$ stat -c "%n %G" /var/log/syslog
/var/log/syslog adm

If the /var/log/syslog file is not group-owned by "adm", this is a finding.

Fix

Configure Ubuntu 24.04 LTS to have adm group-own the /var/log/syslog file by running the following command:

$ sudo chgrp adm /var/log/syslog

Ubuntu 24.04 LTS must configure /var/log/syslog file to be owned by syslog.

STIG ID: UBTU-24-700140 | SRG: SRG-OS-000206-GPOS-00084 | Severity: medium | CCI: CCI-001314 | Vulnerability Id: V-270769

Vulnerability Discussion

Check

Verify that Ubuntu 24.04 LTS configures the /var/log/syslog file to be owned by "syslog" with the following command:

$ stat -c "%n %U" /var/log/syslog
/var/log/syslog syslog

If the "/var/log/syslog" file is not owned by syslog, this is a finding.

Fix

Configure Ubuntu 24.04 LTS to have syslog own the /var/log/syslog file by running the following command:

$ sudo chown syslog /var/log/syslog

Ubuntu 24.04 LTS must configure /var/log/syslog file with mode "0640" or less permissive.

STIG ID: UBTU-24-700150 | SRG: SRG-OS-000206-GPOS-00084 | Severity: medium | CCI: CCI-001314 | Vulnerability Id: V-270770

Vulnerability Discussion

Check

Verify that Ubuntu 24.04 LTS configures the /var/log/syslog file with mode "0640" or less permissive with the following command:

$ stat -c "%n %a" /var/log/syslog
/var/log/syslog 640

If a value of "640" or less permissive is not returned, this is a finding.

Fix

Configure Ubuntu 24.04 LTS to have permissions of "0640" for the /var/log/syslog file by running the following command:

$ sudo chmod 0640 /var/log/syslog

Ubuntu 24.04 LTS must implement nonexecutable data to protect its memory from unauthorized code execution.

STIG ID: UBTU-24-700300 | SRG: SRG-OS-000433-GPOS-00192 | Severity: medium | CCI: CCI-002824 | Vulnerability Id: V-270771

Vulnerability Discussion

Some adversaries launch attacks with the intent of executing code in nonexecutable regions of memory or in memory locations that are prohibited. Security safeguards employed to protect memory include, for example, data execution prevention and address space layout randomization. Data execution prevention safeguards can either be hardware-enforced or software-enforced with hardware providing the greater strength of mechanism.

Examples of attacks are buffer overflow attacks.

Check

Verify the NX (no-execution) bit flag is set on the system with the following command:

$ sudo dmesg | grep -i "execute disable"
[ 0.000000] NX (Execute Disable) protection: active

If "dmesg" does not show "NX (Execute Disable) protection: active", check the cpuinfo settings with the following command:

$ grep flags /proc/cpuinfo | grep -w nx | sort -u
flags : fpu vme de pse tsc ms nx rdtscp lm constant_tsc

If "flags" does not contain the "nx" flag, this is a finding.

Fix

Configure Ubuntu 24.04 LTS to enable NX.

If "nx" is not showing up in "/proc/cpuinfo", and the system's BIOS setup configuration permits toggling the No Execution bit, set it to "enable".

Ubuntu 24.04 LTS must implement address space layout randomization to protect its memory from unauthorized code execution.

STIG ID: UBTU-24-700310 | SRG: SRG-OS-000433-GPOS-00193 | Severity: medium | CCI: CCI-002824 | Vulnerability Id: V-270772

Vulnerability Discussion

Check

Verify Ubuntu 24.04 LTS implements address space layout randomization (ASLR) with the following command:

$ sysctl kernel.randomize_va_space
kernel.randomize_va_space = 2

If nothing is returned, verify the kernel parameter "randomize_va_space" is set to "2" with the following command:

$ cat /proc/sys/kernel/randomize_va_space
2

If "kernel.randomize_va_space" is not set to "2", this is a finding.

Verify that a saved value of the "kernel.randomize_va_space" variable is not defined.

$ sudo egrep -R "^kernel.randomize_va_space=[^2]" /etc/sysctl.conf /etc/sysctl.d

If this returns a result, this is a finding.

Fix

Remove the "kernel.randomize_va_space" entry found in the "/etc/sysctl.conf" file or any file located in the "/etc/sysctl.d/" directory.

After the line has been removed, the kernel settings from all system configuration files must be reloaded before any of the changes will take effect. Run the following command to reload all of the kernel system configuration files:

$ sudo sysctl --system

Ubuntu 24.04 LTS must be configured so that Advance Package Tool (APT) removes all software components after updated versions have been installed.

STIG ID: UBTU-24-700320 | SRG: SRG-OS-000437-GPOS-00194 | Severity: medium | CCI: CCI-002617 | Vulnerability Id: V-270773

Vulnerability Discussion

Previous versions of software components that are not removed from the information system after updates have been installed may be exploited by adversaries. Some information technology products may remove older versions of software automatically from the information system.

Check

Verify APT is configured to remove all software components after updated versions have been installed with the following command:

$ grep -i remove-unused /etc/apt/apt.conf.d/50unattended-upgrades
Unattended-Upgrade::Remove-Unused-Dependencies "true";
Unattended-Upgrade::Remove-Unused-Kernel-Packages "true";

If the "::Remove-Unused-Dependencies" and "::Remove-Unused-Kernel-Packages" parameters are not set to "true", are commented out, or are missing, this is a finding.

Fix

Configure APT to remove all software components after updated versions have been installed.

Add or update the following options to the "/etc/apt/apt.conf.d/50unattended-upgrades" file:

Unattended-Upgrade::Remove-Unused-Dependencies "true";
Unattended-Upgrade::Remove-Unused-Kernel-Packages "true";

Ubuntu 24.04 LTS must be a vendor-supported release.

STIG ID: UBTU-24-700400 | SRG: SRG-OS-000439-GPOS-00195 | Severity: medium | CCI: CCI-002605 | Vulnerability Id: V-270774

Vulnerability Discussion

An operating system release is considered "supported" if the vendor continues to provide security patches for the product. With an unsupported release, it will not be possible to resolve security issues discovered in the system software.

Check

Verify the version of Ubuntu 24.04 LTS is vendor supported with the following command:

$ grep DISTRIB_DESCRIPTION /etc/lsb-release
DISTRIB_DESCRIPTION="Ubuntu 24.04.1 LTS"

If the installed version of Ubuntu 24.04 LTS is not supported, this is a finding.

Fix

Upgrade to a supported version of Ubuntu 24.04 LTS.

Ubuntu 24.04 LTS must be configured so that audit configuration files are not write-accessible by unauthorized users.

STIG ID: UBTU-24-900040 | SRG: SRG-OS-000063-GPOS-00032 | Severity: medium | CCI: CCI-000171 | Vulnerability Id: V-270775

Vulnerability Discussion

Without the capability to restrict which roles and individuals can select which events are audited, unauthorized personnel may be able to prevent the auditing of critical events.

Misconfigured audits may degrade the system's performance by overwhelming the audit log. Misconfigured audits may also make it more difficult to establish, correlate, and investigate the events relating to an incident or identify those responsible for one.

Check

Verify /etc/audit/audit.rules, /etc/audit/rules.d/*, and /etc/audit/auditd.conf files have a mode of "0640" or less permissive with the following command:

$ sudo ls -al /etc/audit/ /etc/audit/rules.d/
/etc/audit/:

-rw-r----- 1 root root 804 Nov 25 11:01 auditd.conf
-rw-r----- 1 root root 9128 Dec 27 09:56 audit.rules
-rw-r----- 1 root root 127 Feb 7 2018 audit-stop.rules

drwxr-x--- 2 root root 4096 Dec 27 09:56 rules.d

/etc/audit/rules.d/:

-rw-r----- 1 root root 244 Dec 27 09:56 audit.rules
-rw-r----- 1 root root 10357 Dec 27 09:56 stig.rules

If /etc/audit/audit.rule, /etc/audit/rules.d/*, or /etc/audit/auditd.conf files have a mode more permissive than "0640", this is a finding.

Fix

Configure /etc/audit/audit.rules, /etc/audit/rules.d/*, and /etc/audit/auditd.conf files to have a mode of "0640" by using the following command:

$ sudo chmod -R 0640 /etc/audit/audit*.{rules,conf} /etc/audit/rules.d/*

Ubuntu 24.04 LTS must permit only authorized accounts to own the audit configuration files.

STIG ID: UBTU-24-900050 | SRG: SRG-OS-000063-GPOS-00032 | Severity: medium | CCI: CCI-000171 | Vulnerability Id: V-270776

Vulnerability Discussion

Check

Verify /etc/audit/audit.rules, /etc/audit/rules.d/*, and /etc/audit/auditd.conf files are owned by "root" account with the following command:

$ sudo ls -al /etc/audit/ /etc/audit/rules.d/
/etc/audit/:

-rw-r----- 1 root root 804 Nov 25 11:01 auditd.conf
-rw-r----- 1 root root 9128 Dec 27 09:56 audit.rules
-rw-r----- 1 root root 127 Feb 7 2018 audit-stop.rules

drwxr-x--- 2 root root 4096 Dec 27 09:56 rules.d

/etc/audit/rules.d/:

-rw-r----- 1 root root 244 Dec 27 09:56 audit.rules
-rw-r----- 1 root root 10357 Dec 27 09:56 stig.rules

If the /etc/audit/audit.rules, /etc/audit/rules.d/*, or /etc/audit/auditd.conf file is owned by a user other than "root", this is a finding.

Fix

Configure /etc/audit/audit.rules, /etc/audit/rules.d/*, and /etc/audit/auditd.conf files to be owned by "root" user by using the following command:

$ sudo chown root /etc/audit/audit*.{rules,conf} /etc/audit/rules.d/*

Ubuntu 24.04 LTS must permit only authorized groups to own the audit configuration files.

STIG ID: UBTU-24-900060 | SRG: SRG-OS-000063-GPOS-00032 | Severity: medium | CCI: CCI-000171 | Vulnerability Id: V-270777

Vulnerability Discussion

Check

Verify /etc/audit/audit.rules, /etc/audit/rules.d/*, and /etc/audit/auditd.conf files are owned by "root" group with the following command:

$ sudo ls -al /etc/audit/ /etc/audit/rules.d/
/etc/audit/:

-rw-r----- 1 root root 804 Nov 25 11:01 auditd.conf
-rw-r----- 1 root root 9128 Dec 27 09:56 audit.rules
-rw-r----- 1 root root 127 Feb 7 2018 audit-stop.rules

drwxr-x--- 2 root root 4096 Dec 27 09:56 rules.d

/etc/audit/rules.d/:

-rw-r----- 1 root root 244 Dec 27 09:56 audit.rules
-rw-r----- 1 root root 10357 Dec 27 09:56 stig.rules

If the "/etc/audit/audit.rules", "/etc/audit/rules.d/*", or "/etc/audit/auditd.conf" file is owned by a group other than "root", this is a finding.

Fix

Configure /etc/audit/audit.rules, /etc/audit/rules.d/*, and /etc/audit/auditd.conf files to be owned by "root" group by using the following command:

$ sudo chown :root /etc/audit/audit*.{rules,conf} /etc/audit/rules.d/*

Ubuntu 24.04 LTS must generate audit records for successful/unsuccessful uses of the su command.

STIG ID: UBTU-24-900070 | SRG: SRG-OS-000064-GPOS-00033 | Severity: medium | CCI: CCI-000172 | Vulnerability Id: V-270778

Vulnerability Discussion

Without generating audit records that are specific to the security and mission needs of the organization, it would be difficult to establish, correlate, and investigate the events relating to an incident or identify those responsible for one.

Audit records can be generated from various components within the information system (e.g., module or policy filter).

Check

Verify Ubuntu 24.04 LTS generates audit records upon successful/unsuccessful attempts to use the "su" command with the following command:

$ sudo auditctl -l | grep /bin/su
-a always,exit -F path=/bin/su -F perm=x -F auid>=1000 -F auid!=-1 -k privileged-priv_change

If the command does not return lines that match the example or the lines are commented out, this is a finding.

Note: The "-k" allows for specifying an arbitrary identifier, and the string after it does not need to match the example output above.

Fix

Configure Ubuntu 24.04 LTS to generate audit records when successful/unsuccessful attempts to use the "su" command occur.

Add or update the following rules in the "/etc/audit/rules.d/stig.rules" file:

-a always,exit -F path=/bin/su -F perm=x -F auid>=1000 -F auid!=-1 -k privileged-priv_change

To reload the rules file, issue the following command:

$ sudo augenrules --load

Ubuntu 24.04 LTS must generate audit records for successful/unsuccessful uses of the chfn command.

STIG ID: UBTU-24-900080 | SRG: SRG-OS-000064-GPOS-00033 | Severity: medium | CCI: CCI-000172 | Vulnerability Id: V-270779

Vulnerability Discussion

Check

Verify Ubuntu 24.04 LTS generates audit records upon successful/unsuccessful attempts to use the "chfn" command with the following command:

$ sudo auditctl -l | grep /usr/bin/chfn
-a always,exit -F path=/usr/bin/chfn -F perm=x -F auid>=1000 -F auid!=-1 -k privileged-chfn

If the command does not return lines that match the example or the lines are commented out, this is a finding.

Note: The "-k" allows for specifying an arbitrary identifier, and the string after it does not need to match the example output above.

Fix

Configure the audit system to generate an audit event for any successful/unsuccessful uses of the "chfn" command.

Add or update the following rules in the "/etc/audit/rules.d/stig.rules" file:

-a always,exit -F path=/usr/bin/chfn -F perm=x -F auid>=1000 -F auid!=-1 -k privileged-chfn

To reload the rules file, issue the following command:

$ sudo augenrules --load

Ubuntu 24.04 LTS must generate audit records for successful/unsuccessful uses of the mount command.

STIG ID: UBTU-24-900090 | SRG: SRG-OS-000064-GPOS-00033 | Severity: medium | CCI: CCI-000172 | Vulnerability Id: V-270780

Vulnerability Discussion

Check

Verify Ubuntu 24.04 LTS generates audit records upon successful/unsuccessful attempts to use the "mount" command with the following command:

$ sudo auditctl -l | grep /usr/bin/mount
-a always,exit -F path=/usr/bin/mount -F perm=x -F auid>=1000 -F auid!=-1 -k privileged-mount

If the command does not return lines that match the example or the lines are commented out, this is a finding.

Note: The "-k" allows for specifying an arbitrary identifier, and the string after it does not need to match the example output above.

Fix

Configure the audit system to generate an audit event for any successful/unsuccessful use of the "mount" command.

Add or update the following rules in the "/etc/audit/rules.d/stig.rules" file:

-a always,exit -F path=/usr/bin/mount -F perm=x -F auid>=1000 -F auid!=-1 -k privileged-mount

To reload the rules file, issue the following command:

$ sudo augenrules --load

Ubuntu 24.04 LTS must generate audit records for successful/unsuccessful uses of the umount command.

STIG ID: UBTU-24-900100 | SRG: SRG-OS-000064-GPOS-00033 | Severity: medium | CCI: CCI-000172 | Vulnerability Id: V-270781

Vulnerability Discussion

Check

Verify Ubuntu 24.04 LTS generates audit records upon successful/unsuccessful attempts to use the "umount" command with the following command:

$ sudo auditctl -l | grep /usr/bin/umount
-a always,exit -F path=/usr/bin/umount -F perm=x -F auid>=1000 -F auid!=-1 -k privileged-umount

If the command does not return lines that match the example or the lines are commented out, this is a finding.

Note: The "-k" allows for specifying an arbitrary identifier, and the string after it does not need to match the example output above.

Fix

Configure the audit system to generate an audit event for any successful/unsuccessful use of the "umount" command.

Add or update the following rules in the "/etc/audit/rules.d/stig.rules" file:

-a always,exit -F path=/usr/bin/umount -F perm=x -F auid>=1000 -F auid!=-1 -k privileged-umount

To reload the rules file, issue the following command:

$ sudo augenrules --load

Ubuntu 24.04 LTS must generate audit records for successful/unsuccessful uses of the ssh-agent command.

STIG ID: UBTU-24-900110 | SRG: SRG-OS-000064-GPOS-00033 | Severity: medium | CCI: CCI-000172 | Vulnerability Id: V-270782

Vulnerability Discussion

Check

Verify Ubuntu 24.04 LTS generates an audit record upon successful/unsuccessful attempts to use the "ssh-agent" command with the following command:

$ sudo auditctl -l | grep /usr/bin/ssh-agent
-a always,exit -F path=/usr/bin/ssh-agent -F perm=x -F auid>=1000 -F auid!=-1 -k privileged-ssh

If the command does not return lines that match the example or the lines are commented out, this is a finding.

Note: The "-k" allows for specifying an arbitrary identifier, and the string after it does not need to match the example output above.

Fix

Configure the audit system to generate an audit event for any successful/unsuccessful use of the "ssh-agent" command.

Add or update the following rules in the "/etc/audit/rules.d/stig.rules" file:

-a always,exit -F path=/usr/bin/ssh-agent -F perm=x -F auid>=1000 -F auid!=-1 -k privileged-ssh

To reload the rules file, issue the following command:

$ sudo augenrules --load

Ubuntu 24.04 LTS must generate audit records for successful/unsuccessful uses of the ssh-keysign command.

STIG ID: UBTU-24-900120 | SRG: SRG-OS-000064-GPOS-00033 | Severity: medium | CCI: CCI-000172 | Vulnerability Id: V-270783

Vulnerability Discussion

Check

Verify Ubuntu 24.04 LTS generates an audit record upon successful/unsuccessful attempts to use the "ssh-keysign" command with the following command:

$ sudo auditctl -l | grep ssh-keysign
-a always,exit -F path=/usr/lib/openssh/ssh-keysign -F perm=x -F auid>=1000 -F auid!=-1 -k privileged-ssh

If the command does not return lines that match the example or the lines are commented out, this is a finding.

Note: The "-k" allows for specifying an arbitrary identifier, and the string after it does not need to match the example output above.

Fix

Configure the audit system to generate an audit event for any successful/unsuccessful use of the "ssh-keysign" command.

Add or update the following rules in the "/etc/audit/rules.d/stig.rules" file:

-a always,exit -F path=/usr/lib/openssh/ssh-keysign -F perm=x -F auid>=1000 -F auid!=-1 -k privileged-ssh

To reload the rules file, issue the following command:

$ sudo augenrules --load

Ubuntu 24.04 LTS must generate audit records for any use of the setxattr, fsetxattr, lsetxattr, removexattr, fremovexattr, and lremovexattr system calls.

STIG ID: UBTU-24-900130 | SRG: SRG-OS-000064-GPOS-00033 | Severity: medium | CCI: CCI-000172 | Vulnerability Id: V-270784

Vulnerability Discussion

Without generating audit records specific to the security and mission needs of the organization, it would be difficult to establish, correlate, and investigate the events relating to an incident or identify those responsible for one.

Audit records can be generated from various components within the information system (e.g., module or policy filter).

The system call rules are loaded into a matching engine that intercepts each syscall that all programs on the system makes. Therefore, it is very important to only use syscall rules when absolutely necessary since these affect performance. The more rules, the bigger the performance hit. The performance is helped, though, by combining syscalls into one rule whenever possible.

Satisfies: SRG-OS-000064-GPOS-00033, SRG-OS-000462-GPOS-00206

Check

Verify Ubuntu 24.04 LTS generates an audit record upon successful/unsuccessful attempts to use the "setxattr", "fsetxattr", "lsetxattr", "removexattr", "fremovexattr", and "lremovexattr" system calls with the following command:

$ sudo auditctl -l | grep xattr
-a always,exit -F arch=b32 -S setxattr,fsetxattr,lsetxattr,removexattr,fremovexattr,lremovexattr -F auid>=1000 -F auid!=-1 -k perm_mod
-a always,exit -F arch=b32 -S setxattr,fsetxattr,lsetxattr,removexattr,fremovexattr,lremovexattr -F auid=0 -k perm_mod
-a always,exit -F arch=b64 -S setxattr,fsetxattr,lsetxattr,removexattr,fremovexattr,lremovexattr -F auid>=1000 -F auid!=-1 -k perm_mod
-a always,exit -F arch=b64 -S setxattr,fsetxattr,lsetxattr,removexattr,fremovexattr,lremovexattr -F auid=0 -k perm_mod

If the command does not return audit rules for the "setxattr", "fsetxattr", "lsetxattr", "removexattr", "fremovexattr" and "lremovexattr" syscalls or the lines are commented out, this is a finding.

Notes:
- For 32-bit architectures, only the 32-bit specific output lines from the commands are required.
- The "-k" allows for specifying an arbitrary identifier, and the string after it does not need to match the example output above.

Fix

Configure the audit system to generate an audit event for any successful/unsuccessful use of the "setxattr", "fsetxattr", "lsetxattr", "removexattr", "fremovexattr", and "lremovexattr" system calls.

Add or update the following rules in the "/etc/audit/rules.d/stig.rules" file:

-a always,exit -F arch=b32 -S setxattr,fsetxattr,lsetxattr,removexattr,fremovexattr,lremovexattr -F auid>=1000 -F auid!=-1 -k perm_mod
-a always,exit -F arch=b32 -S setxattr,fsetxattr,lsetxattr,removexattr,fremovexattr,lremovexattr -F auid=0 -k perm_mod
-a always,exit -F arch=b64 -S setxattr,fsetxattr,lsetxattr,removexattr,fremovexattr,lremovexattr -F auid>=1000 -F auid!=-1 -k perm_mod
-a always,exit -F arch=b64 -S setxattr,fsetxattr,lsetxattr,removexattr,fremovexattr,lremovexattr -F auid=0 -k perm_mod

Note: For 32-bit architectures, only the 32-bit specific entries are required.

To reload the rules file, issue the following command:

$ sudo augenrules --load

Ubuntu 24.04 LTS must generate audit records for successful/unsuccessful uses of the chown, fchown, fchownat, and lchown system calls.

STIG ID: UBTU-24-900140 | SRG: SRG-OS-000064-GPOS-00033 | Severity: medium | CCI: CCI-000172 | Vulnerability Id: V-270785

Vulnerability Discussion

Check

Verify Ubuntu 24.04 LTS generates an audit record upon successful/unsuccessful attempts to use the "chown", "fchown", "fchownat", and "lchown" system calls with the following command:

$ sudo auditctl -l | grep chown
-a always,exit -F arch=b32 -S chown,fchown,fchownat,lchown -F auid>=1000 -F auid!=-1 -k perm_chng
-a always,exit -F arch=b64 -S chown,fchown,fchownat,lchown -F auid>=1000 -F auid!=-1 -k perm_chng

If the command does not return audit rules for the "chown", "fchown", "fchownat", and "lchown" syscalls or the lines are commented out, this is a finding.

Notes:
- For 32-bit architectures, only the 32-bit specific output lines from the commands are required.
- The "-k" allows for specifying an arbitrary identifier, and the string after it does not need to match the example output above.

Fix

Configure the audit system to generate an audit event for any successful/unsuccessful use of the "chown", "fchown", "fchownat", and "lchown" system calls.

Add or update the following rules in the "/etc/audit/rules.d/stig.rules":

-a always,exit -F arch=b32 -S chown,fchown,fchownat,lchown -F auid>=1000 -F auid!=-1 -k perm_chng
-a always,exit -F arch=b64 -S chown,fchown,fchownat,lchown -F auid>=1000 -F auid!=-1 -k perm_chng

Note: For 32-bit architectures, only the 32-bit specific entries are required.

To reload the rules file, issue the following command:

$ sudo augenrules --load

Ubuntu 24.04 LTS must generate audit records for successful/unsuccessful uses of the chmod, fchmod, and fchmodat system calls.

STIG ID: UBTU-24-900150 | SRG: SRG-OS-000064-GPOS-00033 | Severity: medium | CCI: CCI-000172 | Vulnerability Id: V-270786

Vulnerability Discussion

Check

Verify Ubuntu 24.04 LTS generates an audit record upon successful/unsuccessful attempts to use the "chmod", "fchmod", and "fchmodat" system calls with the following command:

$ sudo auditctl -l | grep chmod
-a always,exit -F arch=b32 -S chmod,fchmod,fchmodat -F auid>=1000 -F auid!=-1 -k perm_chng
-a always,exit -F arch=b64 -S chmod,fchmod,fchmodat -F auid>=1000 -F auid!=-1 -k perm_chng

If the command does not return audit rules for the "chmod", "fchmod" and "fchmodat" syscalls or the lines are commented out, this is a finding.

Notes:
- For 32-bit architectures, only the 32-bit specific output lines from the commands are required.
- The "-k" allows for specifying an arbitrary identifier, and the string after it does not need to match the example output above.

Fix

Configure the audit system to generate an audit event for any successful/unsuccessful use of the "chmod", "fchmod", and "fchmodat" system calls.

Add or update the following rules in the "/etc/audit/rules.d/stig.rules":

-a always,exit -F arch=b32 -S chmod,fchmod,fchmodat -F auid>=1000 -F auid!=-1 -k perm_chng
-a always,exit -F arch=b64 -S chmod,fchmod,fchmodat -F auid>=1000 -F auid!=-1 -k perm_chng

Note: For 32-bit architectures, only the 32-bit specific entries are required.

To reload the rules file, issue the following command:

$ sudo augenrules --load

Ubuntu 24.04 LTS must generate audit records for successful/unsuccessful uses of the creat, open, openat, open_by_handle_at, truncate, and ftruncate system calls.

STIG ID: UBTU-24-900160 | SRG: SRG-OS-000064-GPOS-00033 | Severity: medium | CCI: CCI-000172 | Vulnerability Id: V-270787

Vulnerability Discussion

Check

Verify Ubuntu 24.04 LTS generates an audit record upon unsuccessful attempts to use the "creat", "open", "openat", "open_by_handle_at", "truncate", and "ftruncate" system calls with the following command:

$ sudo auditctl -l | grep 'open\|truncate\|creat'
-a always,exit -F arch=b32 -S creat,open,openat,open_by_handle_at,truncate,ftruncate -F exit=-EPERM -F auid>=1000 -F auid!=-1 -k perm_access
-a always,exit -F arch=b32 -S creat,open,openat,open_by_handle_at,truncate,ftruncate -F exit=-EACCES -F auid>=1000 -F auid!=-1 -k perm_access
-a always,exit -F arch=b64 -S creat,open,openat,open_by_handle_at,truncate,ftruncate -F exit=-EPERM -F auid>=1000 -F auid!=-1 -k perm_access
-a always,exit -F arch=b64 -S creat,open,openat,open_by_handle_at,truncate,ftruncate -F exit=-EACCES -F auid>=1000 -F auid!=-1 -k perm_access

If the command does not return audit rules for the "creat", "open", "openat", "open_by_handle_at", "truncate", and "ftruncate" syscalls or the lines are commented out, this is a finding.

Notes:
- For 32-bit architectures, only the 32-bit specific output lines from the commands are required.
- The "-k" allows for specifying an arbitrary identifier, and the string after it does not need to match the example output above.

Fix

Configure the audit system to generate an audit event for any unsuccessful use of the "creat", "open", "openat", "open_by_handle_at", "truncate", and "ftruncate" system calls.

Add or update the following rules in the "/etc/audit/rules.d/stig.rules" file:

-a always,exit -F arch=b32 -S creat,open,openat,open_by_handle_at,truncate,ftruncate -F exit=-EPERM -F auid>=1000 -F auid!=-1 -k perm_access
-a always,exit -F arch=b32 -S creat,open,openat,open_by_handle_at,truncate,ftruncate -F exit=-EACCES -F auid>=1000 -F auid!=-1 -k perm_access
-a always,exit -F arch=b64 -S creat,open,openat,open_by_handle_at,truncate,ftruncate -F exit=-EPERM -F auid>=1000 -F auid!=-1 -k perm_access
-a always,exit -F arch=b64 -S creat,open,openat,open_by_handle_at,truncate,ftruncate -F exit=-EACCES -F auid>=1000 -F auid!=-1 -k perm_access

Note: For 32-bit architectures, only the 32-bit specific entries are required.

To reload the rules file, issue the following command:

$ sudo augenrules --load

Ubuntu 24.04 LTS must generate audit records for successful/unsuccessful uses of the sudo command.

STIG ID: UBTU-24-900170 | SRG: SRG-OS-000064-GPOS-00033 | Severity: medium | CCI: CCI-000172 | Vulnerability Id: V-270788

Vulnerability Discussion

Check

Verify an audit event is generated for any successful/unsuccessful use of the "sudo" command with the following command:

$ sudo auditctl -l | grep /usr/bin/sudo
-a always,exit -F path=/usr/bin/sudo -F perm=x -F auid>=1000 -F auid!=-1 -k priv_cmd

If the command does not return a line that matches the example or the line is commented out, this is a finding.

Note: The "-k" allows for specifying an arbitrary identifier, and the string after it does not need to match the example output above.

Fix

Configure the audit system to generate an audit event for any successful/unsuccessful use of the "sudo" command.

Add or update the following rules in the "/etc/audit/rules.d/stig.rules" file:

-a always,exit -F path=/usr/bin/sudo -F perm=x -F auid>=1000 -F auid!=-1 -k priv_cmd

To reload the rules file, issue the following command:

$ sudo augenrules --load

Ubuntu 24.04 LTS must generate audit records for successful/unsuccessful uses of the sudoedit command.

STIG ID: UBTU-24-900180 | SRG: SRG-OS-000064-GPOS-00033 | Severity: medium | CCI: CCI-000172 | Vulnerability Id: V-270789

Vulnerability Discussion

Check

Verify Ubuntu 24.04 LTS generates an audit record upon successful/unsuccessful attempts to use the "sudoedit" command with the following command:

$ sudo auditctl -l | grep /usr/bin/sudoedit
-a always,exit -F path=/usr/bin/sudoedit -F perm=x -F auid>=1000 -F auid!=-1 -k priv_cmd

If the command does not return a line that matches the example or the line is commented out, this is a finding.

Note: The "-k" allows for specifying an arbitrary identifier, and the string after it does not need to match the example output above.

Fix

Configure the audit system to generate an audit event for any successful/unsuccessful use of the "sudoedit" command.

Add or update the following rules in the "/etc/audit/rules.d/stig.rules":

-a always,exit -F path=/usr/bin/sudoedit -F perm=x -F auid>=1000 -F auid!=-1 -k priv_cmd

To reload the rules file, issue the following command:

$ sudo augenrules --load

Ubuntu 24.04 LTS must generate audit records for successful/unsuccessful uses of the chsh command.

STIG ID: UBTU-24-900190 | SRG: SRG-OS-000064-GPOS-00033 | Severity: medium | CCI: CCI-000172 | Vulnerability Id: V-270790

Vulnerability Discussion

Check

Verify Ubuntu 24.04 LTS generates an audit record upon successful/unsuccessful attempts to use the "chsh" command with the following command:

$ sudo auditctl -l | grep chsh
-a always,exit -F path=/usr/bin/chsh -F perm=x -F auid>=1000 -F auid!=-1 -k priv_cmd

If the command does not return a line that matches the example or the line is commented out, this is a finding.

Note: The "-k" allows for specifying an arbitrary identifier, and the string after it does not need to match the example output above.

Fix

Configure the audit system to generate an audit event for any successful/unsuccessful use of the "chsh" command.

Add or update the following rules in the "/etc/audit/rules.d/stig.rules" file:

-a always,exit -F path=/usr/bin/chsh -F perm=x -F auid>=1000 -F auid!=-1 -k priv_cmd

To reload the rules file, issue the following command:

$ sudo augenrules --load

Ubuntu 24.04 LTS must generate audit records for successful/unsuccessful uses of the newgrp command.

STIG ID: UBTU-24-900200 | SRG: SRG-OS-000064-GPOS-00033 | Severity: medium | CCI: CCI-000172 | Vulnerability Id: V-270791

Vulnerability Discussion

Check

Verify Ubuntu 24.04 LTS generates an audit record upon successful/unsuccessful attempts to use the "newgrp" command with the following command:

$ sudo auditctl -l | grep newgrp
-a always,exit -F path=/usr/bin/newgrp -F perm=x -F auid>=1000 -F auid!=-1 -k priv_cmd

If the command does not return a line that matches the example or the line is commented out, this is a finding.

Note: The "-k" allows for specifying an arbitrary identifier, and the string after it does not need to match the example output above.

Fix

Configure the audit system to generate an audit event for any successful/unsuccessful use of the "newgrp" command.

Add or update the following rules in the "/etc/audit/rules.d/stig.rules" file:

-a always,exit -F path=/usr/bin/newgrp -F perm=x -F auid>=1000 -F auid!=-1 -k priv_cmd

To reload the rules file, issue the following command:

$ sudo augenrules --load

Ubuntu 24.04 LTS must generate audit records for successful/unsuccessful uses of the chcon command.

STIG ID: UBTU-24-900210 | SRG: SRG-OS-000064-GPOS-00033 | Severity: medium | CCI: CCI-000172 | Vulnerability Id: V-270792

Vulnerability Discussion

Check

Verify Ubuntu 24.04 LTS generates an audit record upon successful/unsuccessful attempts to use the "chcon" command with the following command:

$ sudo auditctl -l | grep chcon
-a always,exit -F path=/usr/bin/chcon -F perm=x -F auid>=1000 -F auid!=-1 -k perm_chng

If the command does not return a line that matches the example or the line is commented out, this is a finding.

Note: The "-k" allows for specifying an arbitrary identifier, and the string after it does not need to match the example output above.

Fix

Configure the audit system to generate an audit event for any successful/unsuccessful use of the "chcon" command.

Add or update the following rules in the "/etc/audit/rules.d/stig.rules" file:

-a always,exit -F path=/usr/bin/chcon -F perm=x -F auid>=1000 -F auid!=-1 -k perm_chng

To reload the rules file, issue the following command:

$ sudo augenrules --load

Ubuntu 24.04 LTS must generate audit records for successful/unsuccessful uses of the apparmor_parser command.

STIG ID: UBTU-24-900220 | SRG: SRG-OS-000064-GPOS-00033 | Severity: medium | CCI: CCI-000172 | Vulnerability Id: V-270793

Vulnerability Discussion

Check

Verify Ubuntu 24.04 LTS generates an audit record upon successful/unsuccessful attempts to use the "apparmor_parser" command with the following command:

$ sudo auditctl -l | grep apparmor_parser
-a always,exit -F path=/sbin/apparmor_parser -F perm=x -F auid>=1000 -F auid!=-1 -k perm_chng

If the command does not return a line that matches the example or the line is commented out, this is a finding.

Note: The "-k" allows for specifying an arbitrary identifier, and the string after it does not need to match the example output above.

Fix

Configure the audit system to generate an audit event for any successful/unsuccessful use of the "apparmor_parser" command.

Add or update the following rules in the "/etc/audit/rules.d/stig.rules" file:

-a always,exit -F path=/sbin/apparmor_parser -F perm=x -F auid>=1000 -F auid!=-1 -k perm_chng

To reload the rules file, issue the following command:

$ sudo augenrules --load

Ubuntu 24.04 LTS must generate audit records for successful/unsuccessful uses of the setfacl command.

STIG ID: UBTU-24-900230 | SRG: SRG-OS-000064-GPOS-00033 | Severity: medium | CCI: CCI-000172 | Vulnerability Id: V-270794

Vulnerability Discussion

Check

Verify Ubuntu 24.04 LTS generates an audit record upon successful/unsuccessful attempts to use the "setfacl" command with the following command:

$ sudo auditctl -l | grep setfacl
-a always,exit -F path=/usr/bin/setfacl -F perm=x -F auid>=1000 -F auid!=-1 -k perm_chng

If the command does not return a line that matches the example or the line is commented out, this is a finding.

Note: The "-k" allows for specifying an arbitrary identifier, and the string after it does not need to match the example output above.

Fix

Configure the audit system to generate an audit event for any successful/unsuccessful use of the "setfacl" command.

Add or update the following rules in the "/etc/audit/rules.d/stig.rules" file:

-a always,exit -F path=/usr/bin/setfacl -F perm=x -F auid>=1000 -F auid!=-1 -k perm_chng

To reload the rules file, issue the following command:

$ sudo augenrules --load

Ubuntu 24.04 LTS must generate audit records for successful/unsuccessful uses of the chacl command.

STIG ID: UBTU-24-900240 | SRG: SRG-OS-000064-GPOS-00033 | Severity: medium | CCI: CCI-000172 | Vulnerability Id: V-270795

Vulnerability Discussion

Check

Verify Ubuntu 24.04 LTS generates an audit record upon successful/unsuccessful attempts to use the "chacl" command with the following command:

$ sudo audtctl -l | grep chacl
-a always,exit -F path=/usr/bin/chacl -F perm=x -F auid>=1000 -F auid!=-1 -k perm_chng

If the command does not return a line that matches the example or the line is commented out, this is a finding.

Note: The "-k" allows for specifying an arbitrary identifier, and the string after it does not need to match the example output above.

Fix

Configure the audit system to generate an audit event for any successful/unsuccessful use of the "chacl" command.

Add or update the following rules in the "/etc/audit/rules.d/stig.rules" file:

-a always,exit -F path=/usr/bin/chacl -F perm=x -F auid>=1000 -F auid!=-1 -k perm_chng

To reload the rules file, issue the following command:

$ sudo augenrules --load

Ubuntu 24.04 LTS must generate audit records for the use and modification of faillog file.

STIG ID: UBTU-24-900250 | SRG: SRG-OS-000064-GPOS-00033 | Severity: medium | CCI: CCI-000172 | Vulnerability Id: V-270796

Vulnerability Discussion

Check

Verify Ubuntu 24.04 LTS generates an audit record upon successful/unsuccessful modifications to the "faillog" file with the following command:

$ sudo auditctl -l | grep faillog
-w /var/log/faillog -p wa -k logins

If the command does not return a line that matches the example or the line is commented out, this is a finding.

Note: The "-k" allows for specifying an arbitrary identifier, and the string after it does not need to match the example output above.

Fix

Configure the audit system to generate an audit event for any successful/unsuccessful modifications to the "faillog" file.

Add or update the following rules in the "/etc/audit/rules.d/stig.rules" file:

-w /var/log/faillog -p wa -k logins

To reload the rules file, issue the following command:

$ sudo augenrules --load

Ubuntu 24.04 LTS must generate audit records for the use and modification of the lastlog file.

STIG ID: UBTU-24-900260 | SRG: SRG-OS-000064-GPOS-00033 | Severity: medium | CCI: CCI-000172 | Vulnerability Id: V-270797

Vulnerability Discussion

Check

Verify Ubuntu 24.04 LTS generates an audit record when successful/unsuccessful modifications to the "lastlog" file occur with the following command:

$ sudo auditctl -l | grep lastlog
-w /var/log/lastlog -p wa -k logins

If the command does not return a line that matches the example or the line is commented out, this is a finding.

Note: The "-k" allows for specifying an arbitrary identifier, and the string after it does not need to match the example output above.

Fix

Configure the audit system to generate an audit event for any successful/unsuccessful modifications to the "lastlog" file.

Add or update the following rules in the "/etc/audit/rules.d/stig.rules" file:

-w /var/log/lastlog -p wa -k logins

To reload the rules file, issue the following command:

$ sudo augenrules --load

Ubuntu 24.04 LTS must generate audit records for successful/unsuccessful uses of the passwd command.

STIG ID: UBTU-24-900270 | SRG: SRG-OS-000064-GPOS-00033 | Severity: medium | CCI: CCI-000172 | Vulnerability Id: V-270798

Vulnerability Discussion

Check

Verify that an audit event is generated for any successful/unsuccessful use of the "passwd" command with the following command:

$ sudo auditctl -l | grep -w passwd
-a always,exit -S all -F path=/usr/bin/passwd -F perm=x -F auid>=1000 -F auid!=-1 -F key=privileged-passwd

If the command does not return a line that matches the example or the line is commented out, this is a finding.

Note: The "-k" allows for specifying an arbitrary identifier, and the string after it does not need to match the example output above.

Fix

Configure the audit system to generate an audit event for any successful/unsuccessful uses of the "passwd" command.

Add or update the following rule in the "/etc/audit/rules.d/stig.rules" file:

-a always,exit -F path=/usr/bin/passwd -F perm=x -F auid>=1000 -F auid!=-1 -k privileged-passwd

To reload the rules file, issue the following command:

$ sudo augenrules --load

Ubuntu 24.04 LTS must generate audit records for successful/unsuccessful uses of the unix_update command.

STIG ID: UBTU-24-900280 | SRG: SRG-OS-000064-GPOS-00033 | Severity: medium | CCI: CCI-000172 | Vulnerability Id: V-270799

Vulnerability Discussion

Check

Verify that an audit event is generated for any successful/unsuccessful use of the "unix_update" command with the following command:

$ sudo auditctl -l | grep -w unix_update
-a always,exit -F path=/sbin/unix_update -F perm=x -F auid>=1000 -F auid!=-1 -k privileged-unix-update

If the command does not return a line that matches the example or the line is commented out, this is a finding.

Note: The "-k" allows for specifying an arbitrary identifier, and the string after it does not need to match the example output above.

Fix

Configure the audit system to generate an audit event for any successful/unsuccessful uses of the "unix_update" command.

Add or update the following rules in the "/etc/audit/rules.d/stig.rules" file:

-a always,exit -F path=/sbin/unix_update -F perm=x -F auid>=1000 -F auid!=-1 -k privileged-unix-update

To reload the rules file, issue the following command:

$ sudo augenrules --load

Ubuntu 24.04 LTS must generate audit records for successful/unsuccessful uses of the gpasswd command.

STIG ID: UBTU-24-900290 | SRG: SRG-OS-000064-GPOS-00033 | Severity: medium | CCI: CCI-000172 | Vulnerability Id: V-270800

Vulnerability Discussion

Check

Verify that an audit event is generated for any successful/unsuccessful use of the "gpasswd" command with the following command:

$ sudo auditctl -l | grep -w gpasswd
-a always,exit -F path=/usr/bin/gpasswd -F perm=x -F auid>=1000 -F auid!=-1 -k privileged-gpasswd

If the command does not return a line that matches the example or the line is commented out, this is a finding.

Note: The "-k" allows for specifying an arbitrary identifier, and the string after it does not need to match the example output above.

Fix

Configure the audit system to generate an audit event for any successful/unsuccessful uses of the "gpasswd" command.

Add or update the following rules in the "/etc/audit/rules.d/stig.rules" file:

-a always,exit -F path=/usr/bin/gpasswd -F perm=x -F auid>=1000 -F auid!=-1 -k privileged-gpasswd

To reload the rules file, issue the following command:

$ sudo augenrules --load

Ubuntu 24.04 LTS must generate audit records for successful/unsuccessful uses of the chage command.

STIG ID: UBTU-24-900300 | SRG: SRG-OS-000064-GPOS-00033 | Severity: medium | CCI: CCI-000172 | Vulnerability Id: V-270801

Vulnerability Discussion

Check

Verify that an audit event is generated for any successful/unsuccessful use of the "chage" command with the following command:

$ sudo auditctl -l | grep -w chage
-a always,exit -F path=/usr/bin/chage -F perm=x -F auid>=1000 -F auid!=-1 -k privileged-chage

If the command does not return a line that matches the example or the line is commented out, this is a finding.

Note: The "-k" allows for specifying an arbitrary identifier, and the string after it does not need to match the example output above.

Fix

Configure the audit system to generate an audit event for any successful/unsuccessful uses of the "chage" command.

Add or update the following rules in the "/etc/audit/rules.d/stig.rules" file:

-a always,exit -F path=/usr/bin/chage -F perm=x -F auid>=1000 -F auid!=-1 -k privileged-chage

To reload the rules file, issue the following command:

$ sudo augenrules --load

Ubuntu 24.04 LTS must generate audit records for successful/unsuccessful uses of the usermod command.

STIG ID: UBTU-24-900310 | SRG: SRG-OS-000064-GPOS-00033 | Severity: medium | CCI: CCI-000172 | Vulnerability Id: V-270802

Vulnerability Discussion

Check

Verify an audit event is generated for any successful/unsuccessful use of the "usermod" command with the following command:

$ sudo auditctl -l | grep -w usermod
-a always,exit -F path=/usr/sbin/usermod -F perm=x -F auid>=1000 -F auid!=-1 -k privileged-usermod

If the command does not return a line that matches the example or the line is commented out, this is a finding.

Note: The "-k" allows for specifying an arbitrary identifier, and the string after it does not need to match the example output above.

Fix

Configure the audit system to generate an audit event for any successful/unsuccessful uses of the "usermod" command.

Add or update the following rules in the "/etc/audit/rules.d/stig.rules" file:

-a always,exit -F path=/usr/sbin/usermod -F perm=x -F auid>=1000 -F auid!=-1 -k privileged-usermod

To reload the rules file, issue the following command:

$ sudo augenrules --load

Ubuntu 24.04 LTS must generate audit records for successful/unsuccessful uses of the crontab command.

STIG ID: UBTU-24-900320 | SRG: SRG-OS-000064-GPOS-00033 | Severity: medium | CCI: CCI-000172 | Vulnerability Id: V-270803

Vulnerability Discussion

Check

Verify an audit event is generated for any successful/unsuccessful use of the "crontab" command with the following command:

$ sudo auditctl -l | grep -w crontab
-a always,exit -F path=/usr/bin/crontab -F perm=x -F auid>=1000 -F auid!=-1 -k privileged-crontab

If the command does not return a line that matches the example or the line is commented out, this is a finding.

Note: The "-k" allows for specifying an arbitrary identifier, and the string after it does not need to match the example output above.

Fix

Configure the audit system to generate an audit event for any successful/unsuccessful uses of the "crontab" command.

Add or update the following rules in the "/etc/audit/rules.d/stig.rules" file:

-a always,exit -F path=/usr/bin/crontab -F perm=x -F auid>=1000 -F auid!=-1 -k privileged-crontab

To reload the rules file, issue the following command:

$ sudo augenrules --load

Ubuntu 24.04 LTS must generate audit records for successful/unsuccessful uses of the pam_timestamp_check command.

STIG ID: UBTU-24-900330 | SRG: SRG-OS-000064-GPOS-00033 | Severity: medium | CCI: CCI-000172 | Vulnerability Id: V-270804

Vulnerability Discussion

Check

Verify an audit event is generated for any successful/unsuccessful use of the "pam_timestamp_check" command with the following command:

$ sudo auditctl -l | grep -w pam_timestamp_check
-a always,exit -F path=/usr/sbin/pam_timestamp_check -F perm=x -F auid>=1000 -F auid!=-1 -k privileged-pam_timestamp_check

If the command does not return a line that matches the example or the line is commented out, this is a finding.

Note: The "-k" allows for specifying an arbitrary identifier, and the string after it does not need to match the example output above.

Fix

Configure the audit system to generate an audit event for any successful/unsuccessful uses of the "pam_timestamp_check" command.

Add or update the following rules in the "/etc/audit/rules.d/stig.rules" file:

-a always,exit -F path=/usr/sbin/pam_timestamp_check -F perm=x -F auid>=1000 -F auid!=-1 -k privileged-pam_timestamp_check

To reload the rules file, issue the following command:

$ sudo augenrules --load

Ubuntu 24.04 LTS must generate audit records for successful/unsuccessful uses of the init_module and finit_module syscalls.

STIG ID: UBTU-24-900340 | SRG: SRG-OS-000064-GPOS-00033 | Severity: medium | CCI: CCI-000172 | Vulnerability Id: V-270805

Vulnerability Discussion

Check

Verify Ubuntu 24.04 LTS generates an audit record for any successful/unsuccessful attempts to use the "init_module" and "finit_module" syscalls with the following command:

$ sudo auditctl -l | grep init_module
-a always,exit -F arch=b32 -S init_module,finit_module -F auid>=1000 -F auid!=-1 -k module_chng
-a always,exit -F arch=b64 -S init_module,finit_module -F auid>=1000 -F auid!=-1 -k module_chng

If the command does not return audit rules for the "init_module" and "finit_module" syscalls or the lines are commented out, this is a finding.

Notes:
- For 32-bit architectures, only the 32-bit specific output lines from the commands are required.
- The "-k" allows for specifying an arbitrary identifier, and the string after it does not need to match the example output above.

Fix

Configure the audit system to generate an audit event for any successful/unsuccessful use of the "init_module" and "finit_module" syscalls.

Add or update the following rules in the "/etc/audit/rules.d/stig.rules" file:

-a always,exit -F arch=b32 -S init_module,finit_module -F auid>=1000 -F auid!=-1 -k module_chng
-a always,exit -F arch=b64 -S init_module,finit_module -F auid>=1000 -F auid!=-1 -k module_chng

Note: For 32-bit architectures, only the 32-bit specific entries are required.

To reload the rules file, issue the following command:

$ sudo augenrules --load

Ubuntu 24.04 LTS must generate audit records for successful/unsuccessful uses of the delete_module syscall.

STIG ID: UBTU-24-900350 | SRG: SRG-OS-000064-GPOS-00033 | Severity: medium | CCI: CCI-000172 | Vulnerability Id: V-270806

Vulnerability Discussion

Check

Verify Ubuntu 24.04 LTS generates an audit record for any successful/unsuccessful attempts to use the "delete_module" syscall with the following command:

$ sudo auditctl -l | grep -w delete_module
-a always,exit -F arch=b32 -S delete_module -F auid>=1000 -F auid!=-1 -k module_chng
-a always,exit -F arch=b64 -S delete_module -F auid>=1000 -F auid!=-1 -k module_chng

If the command does not return a line that matches the example or the line is commented out, this is a finding.

Notes:
- For 32-bit architectures, only the 32-bit specific output lines from the commands are required.
- The "-k" allows for specifying an arbitrary identifier, and the string after it does not need to match the example output above.

Fix

Configure the audit system to generate an audit event for any successful/unsuccessful use of the "delete_module" syscall.

Add or update the following rules in the "/etc/audit/rules.d/stig.rules" file:

-a always,exit -F arch=b32 -S delete_module -F auid>=1000 -F auid!=-1 -k module_chng
-a always,exit -F arch=b64 -S delete_module -F auid>=1000 -F auid!=-1 -k module_chng

Note: For 32-bit architectures, only the 32-bit specific entries are required.

To reload the rules file, issue the following command:

$ sudo augenrules --load

Ubuntu 24.04 LTS must generate audit records when successful/unsuccessful attempts to modify the /etc/sudoers file occur.

STIG ID: UBTU-24-900510 | SRG: SRG-OS-000466-GPOS-00210 | Severity: medium | CCI: CCI-000172 | Vulnerability Id: V-270807

Vulnerability Discussion

Check

Verify Ubuntu 24.04 LTS generates audit records for all modifications that affect "/etc/sudoers" with the following command:

$ sudo auditctl -l | grep sudoers
-w /etc/sudoers -p wa -k privilege_modification

If the command does not return a line that matches the example or the line is commented out, this is a finding.

Note: The "-k" allows for specifying an arbitrary identifier, and the string after it does not need to match the example output above.

Fix

Configure Ubuntu 24.04 LTS to generate audit records for all modifications that affect "/etc/sudoers".

Add or update the following rule to "/etc/audit/rules.d/stig.rules":

-w /etc/sudoers -p wa -k privilege_modification

To reload the rules file, issue the following command:

$ sudo augenrules --load

Ubuntu 24.04 LTS must generate audit records when successful/unsuccessful attempts to modify the /etc/sudoers.d directory occur.

STIG ID: UBTU-24-900520 | SRG: SRG-OS-000466-GPOS-00210 | Severity: medium | CCI: CCI-000172 | Vulnerability Id: V-270808

Vulnerability Discussion

Check

Verify Ubuntu 24.04 LTS generates audit records for all modifications that affect "/etc/sudoers.d" directory with the following command:

$ sudo auditctl -l | grep sudoers.d
-w /etc/sudoers.d -p wa -k privilege_modification

If the command does not return a line that matches the example or the line is commented out, this is a finding.

Note: The "-k" allows for specifying an arbitrary identifier, and the string after it does not need to match the example output above.

Fix

Configure Ubuntu 24.04 LTS to generate audit records for all modifications that affect "/etc/sudoers.d" directory.

Add or update the following rule to "/etc/audit/rules.d/stig.rules":

-w /etc/sudoers.d -p wa -k privilege_modification

To reload the rules file, issue the following command:

$ sudo augenrules --load

Ubuntu 24.04 LTS must generate audit records for any successful/unsuccessful use of unlink, unlinkat, rename, renameat, and rmdir system calls.

STIG ID: UBTU-24-900540 | SRG: SRG-OS-000468-GPOS-00212 | Severity: medium | CCI: CCI-000172 | Vulnerability Id: V-270809

Vulnerability Discussion

Check

Verify Ubuntu 24.04 LTS generates audit records for any successful/unsuccessful use of "unlink", "unlinkat", "rename", "renameat", and "rmdir" system calls with the following command:

$ sudo auditctl -l | grep 'unlink\|rename\|rmdir'
-a always,exit -F arch=b64 -S unlink,unlinkat,rename,renameat,rmdir -F auid>=1000 -F auid!=-1 -F key=delete
-a always,exit -F arch=b32 -S unlink,unlinkat,rename,renameat,rmdir -F auid>=1000 -F auid!=-1 -F key=delete

If the command does not return audit rules for the "unlink", "unlinkat", "rename", "renameat", and "rmdir" syscalls or the lines are commented out, this is a finding.

Notes:
- For 32-bit architectures, only the 32-bit specific output lines from the commands are required.
- The "-k" allows for specifying an arbitrary identifier, and the string after it does not need to match the example output above.

Fix

Configure the audit system to generate audit events for any successful/unsuccessful use of "unlink", "unlinkat", "rename", "renameat", and "rmdir" system calls.

Add or update the following rules in the "/etc/audit/rules.d/stig.rules" file:

-a always,exit -F arch=b64 -S unlink,unlinkat,rename,renameat,rmdir -F auid>=1000 -F auid!=-1 -k delete
-a always,exit -F arch=b32 -S unlink,unlinkat,rename,renameat,rmdir -F auid>=1000 -F auid!=-1 -k delete

Note: For 32-bit architectures, only the 32-bit specific entries are required.

To reload the rules file, issue the following command:

$ sudo augenrules --load

Ubuntu 24.04 LTS must generate audit records for the /var/log/wtmp file.

STIG ID: UBTU-24-900590 | SRG: SRG-OS-000472-GPOS-00217 | Severity: medium | CCI: CCI-000172 | Vulnerability Id: V-270810

Vulnerability Discussion

Check

Verify Ubuntu 24.04 LTS generates audit records showing start and stop times for user access to the system via the "/var/log/wtmp" file with the following command:

$ sudo auditctl -l | grep '/var/log/wtmp'
-w /var/log/wtmp -p wa -k logins

If the command does not return a line matching the example or the line is commented out, this is a finding.

Note: The "-k" allows for specifying an arbitrary identifier, and the string after it does not need to match the example output above.

Fix

Configure the audit system to generate audit events showing start and stop times for user access via the "/var/log/wtmp" file.

Add or update the following rules in the "/etc/audit/rules.d/stig.rules" file:

-w /var/log/wtmp -p wa -k logins

To reload the rules file, issue the following command:

$ sudo augenrules --load

Ubuntu 24.04 LTS must generate audit records for the /var/run/utmp file.

STIG ID: UBTU-24-900600 | SRG: SRG-OS-000472-GPOS-00217 | Severity: medium | CCI: CCI-000172 | Vulnerability Id: V-270811

Vulnerability Discussion

Check

Verify Ubuntu 24.04 LTS generates audit records showing start and stop times for user access to the system via the "/var/run/utmp" file with the following command:

$ sudo auditctl -l | grep '/var/run/utmp'
-w /var/run/utmp -p wa -k logins

If the command does not return a line matching the example or the line is commented out, this is a finding.

Note: The "-k" allows for specifying an arbitrary identifier, and the string after it does not need to match the example output above.

Fix

Configure the audit system to generate audit events showing start and stop times for user access via the "/var/run/utmp" file.

Add or update the following rules in the "/etc/audit/rules.d/stig.rules" file:

-w /var/run/utmp -p wa -k logins

To reload the rules file, issue the following command:

$ sudo augenrules --load

Ubuntu 24.04 LTS must generate audit records for the /var/log/btmp file.

STIG ID: UBTU-24-900610 | SRG: SRG-OS-000472-GPOS-00217 | Severity: medium | CCI: CCI-000172 | Vulnerability Id: V-270812

Vulnerability Discussion

Check

Verify Ubuntu 24.04 LTS generates audit records showing start and stop times for user access to the system via the "/var/log/btmp" file with the following command:

$ sudo auditctl -l | grep '/var/log/btmp'
-w /var/log/btmp -p wa -k logins

If the command does not return a line matching the example or the line is commented out, this is a finding.

Note: The "-k" allows for specifying an arbitrary identifier, and the string after it does not need to match the example output above.

Fix

Configure the audit system to generate audit events showing start and stop times for user access via the "/var/log/btmp file".

Add or update the following rules in the "/etc/audit/rules.d/stig.rules" file:

-w /var/log/btmp -p wa -k logins

To reload the rules file, issue the following command:

$ sudo augenrules --load

Ubuntu 24.04 LTS must generate audit records when successful/unsuccessful attempts to use modprobe command.

STIG ID: UBTU-24-900730 | SRG: SRG-OS-000477-GPOS-00222 | Severity: medium | CCI: CCI-000172 | Vulnerability Id: V-270813

Vulnerability Discussion

Check

Verify if Ubuntu 24.04 LTS is configured to audit the execution of the module management program "modprobe" with the following command:

$ sudo auditctl -l | grep '/sbin/modprobe'
-w /sbin/modprobe -p x -k modules

If the command does not return a line, or the line is commented out, this is a finding.

Note: The "-k" allows for specifying an arbitrary identifier, and the string after it does not need to match the example output above.

Fix

Configure Ubuntu 24.04 LTS to audit the execution of the module management program "modprobe".

Add or update the following rule in the "/etc/audit/rules.d/stig.rules" file:

-w /sbin/modprobe -p x -k modules

To reload the rules file, issue the following command:

$ sudo augenrules --load

Ubuntu 24.04 LTS must generate audit records when successful/unsuccessful attempts to use the kmod command.

STIG ID: UBTU-24-900740 | SRG: SRG-OS-000477-GPOS-00222 | Severity: medium | CCI: CCI-000172 | Vulnerability Id: V-270814

Vulnerability Discussion

Check

Verify Ubuntu 24.04 LTS is configured to audit the execution of the module management program "kmod" with the following command:

$ sudo auditctl -l | grep kmod
-w /bin/kmod -p x -k module

If the command does not return a line, or the line is commented out, this is a finding.

Note: The "-k" allows for specifying an arbitrary identifier, and the string after it does not need to match the example output above.

Fix

Configure Ubuntu 24.04 LTS to audit the execution of the module management program "kmod".

Add or update the following rule in the "/etc/audit/rules.d/stig.rules" file:

-w /bin/kmod -p x -k modules

To reload the rules file, issue the following command:

$ sudo augenrules --load

Ubuntu 24.04 LTS must generate audit records when successful/unsuccessful attempts to use the fdisk command.

STIG ID: UBTU-24-900750 | SRG: SRG-OS-000477-GPOS-00222 | Severity: medium | CCI: CCI-000172 | Vulnerability Id: V-270815

Vulnerability Discussion

Check

Verify Ubuntu 24.04 LTS is configured to audit the execution of the partition management program "fdisk" with the following command:

$ sudo auditctl -l | grep fdisk
-w /usr/sbin/fdisk -p x -k fdisk

If the command does not return a line, or the line is commented out, this is a finding.

Note: The "-k" allows for specifying an arbitrary identifier, and the string after it does not need to match the example output above.

Fix

Configure Ubuntu 24.04 LTS to audit the execution of the partition management program "fdisk".

Add or update the following rule in the "/etc/audit/rules.d/stig.rules" file:

-w /usr/sbin/fdisk -p x -k fdisk

To reload the rules file, issue the following command:

$ sudo augenrules --load

Ubuntu 24.04 LTS must allocate audit record storage capacity to store at least one week's worth of audit records, when audit records are not immediately sent to a central audit record storage facility.

STIG ID: UBTU-24-900920 | SRG: SRG-OS-000341-GPOS-00132 | Severity: low | CCI: CCI-001849 | Vulnerability Id: V-270816

Vulnerability Discussion

To ensure operating systems have a sufficient storage capacity in which to write the audit logs, operating systems must be able to allocate audit record storage capacity.

The task of allocating audit record storage capacity is usually performed during initial installation of Ubuntu 24.04 LTS.

Check

Verify Ubuntu 24.04 LTS allocates audit record storage capacity to store at least one week's worth of audit records when audit records are not immediately sent to a central audit record storage facility.

Determine which partition the audit records are being written to with the following command:

$ sudo grep ^log_file /etc/audit/auditd.conf
log_file = /var/log/audit/audit.log

Check the size of the partition that audit records are written to (with the example being "/var/log/audit/") with the following command:

$ sudo df -h /var/log/audit/
/dev/sda2 24G 10.4G 13.6G 43% /var/log/audit

If the audit records are not written to a partition made specifically for audit records ("/var/log/audit" is a separate partition), determine the amount of space being used by other files in the partition with the following command:

$ sudo du -sh [audit_partition]
1.8G /var/log/audit

Note: The partition size needed to capture a week's worth of audit records is based on the activity level of the system and the total storage capacity available.

If the audit record partition is not allocated for sufficient storage capacity, this is a finding.

Fix

Allocate enough storage capacity for at least one week's worth of audit records when audit records are not immediately sent to a central audit record storage facility.

If audit records are stored on a partition made specifically for audit records, use the "parted" program to resize the partition with sufficient space to contain one week's worth of audit records.

If audit records are not stored on a partition made specifically for audit records, a new partition with sufficient amount of space will need be to be created.

Set the auditd server to point to the mount point where the audit records must be located:

$ sudo sed -i -E 's@^(log_file\s*=\s*).*@\1 <log mountpoint>/audit.log@' /etc/audit/auditd.conf

where <log mountpoint> is the aforementioned mount point.

Ubuntu 24.04 LTS must have a crontab script running weekly to offload audit events of standalone systems.

STIG ID: UBTU-24-900950 | SRG: SRG-OS-000479-GPOS-00224 | Severity: low | CCI: CCI-001851 | Vulnerability Id: V-270817

Vulnerability Discussion

Information stored in one location is vulnerable to accidental or incidental deletion or alteration.

Offloading is a common process in information systems with limited audit storage capacity.

Check

Note: If this is an interconnected system, this is not applicable.

Verify there is a script that offloads audit data and that script runs weekly with the following command:

$ ls /etc/cron.weekly
audit-offload

Check if the script inside the file offloads audit logs to external media.

If the script file does not exist or does not offload audit logs, this is a finding.

Fix

Create a script that offloads audit logs to external media and runs weekly.

The script must be located in the "/etc/cron.weekly" directory.

Ubuntu 24.04 LTS must immediately notify the system administrator (SA) and information system security officer (ISSO) (at a minimum) when allocated audit record storage volume reaches 75 percent of the repository maximum audit record storage capacity.

STIG ID: UBTU-24-900960 | SRG: SRG-OS-000343-GPOS-00134 | Severity: low | CCI: CCI-001855 | Vulnerability Id: V-270818

Vulnerability Discussion

If security personnel are not notified immediately when storage volume reaches 75 percent utilization, they are unable to plan for audit record storage capacity expansion.

Check

Verify Ubuntu 24.04 LTS notifies the SA and ISSO (at a minimum) when allocated audit record storage volume reaches 75 percent of the repository maximum audit record storage capacity with the following command:

Note: If the space_left_action is set to "email", an email package must be available.

$ sudo grep ^space_left_action /etc/audit/auditd.conf
space_left_action email

$ sudo grep ^space_left /etc/audit/auditd.conf
space_left 250000

If the "space_left" parameter is set to "syslog", is missing, set to blanks, or set to a value less than 25 percent of the space free in the allocated audit record storage, this is a finding.

If the "space_left_action" parameter is missing or set to blanks, this is a finding.

If the "space_left_action" is set to "email", check the value of the "action_mail_acct" parameter with the following command:

$ sudo grep ^action_mail_acct /etc/audit/auditd.conf
action_mail_acct root@localhost

The "action_mail_acct" parameter, if missing, defaults to "root". If the "action_mail_acct parameter" is not set to the email address of the SA(s) and/or ISSO, this is a finding.

If the "space_left_action" is set to "exec", the system executes a designated script. If this script informs the SA of the event, this is not a finding.

Fix

Edit "/etc/audit/auditd.conf" and set the "space_left_action" parameter to "exec" or "email".

If the "space_left_action" parameter is set to "email", set the "action_mail_acct" parameter to an email address for the SA and ISSO.

If the "space_left_action" parameter is set to "exec", ensure the command being executed notifies the SA and ISSO.

Edit "/etc/audit/auditd.conf" and set the "space_left" parameter to be at least 25 percent of the repository maximum audit record storage capacity.

Ubuntu 24.04 LTS must alert the system administrator (SA) and information system security officer (ISSO) (at a minimum) in the event of an audit processing failure.

STIG ID: UBTU-24-900980 | SRG: SRG-OS-000046-GPOS-00022 | Severity: low | CCI: CCI-000139 | Vulnerability Id: V-270819

Vulnerability Discussion

It is critical for the appropriate personnel to be aware if a system is at risk of failing to process audit logs as required. Without this notification, the security personnel may be unaware of an impending failure of the audit capability, and system operation may be adversely affected.

Audit processing failures include software/hardware errors, failures in the audit capturing mechanisms, and audit storage capacity being reached or exceeded.

This requirement applies to each audit data storage repository (i.e., distinct information system component where audit records are stored), the centralized audit storage capacity of organizations (i.e., all audit data storage repositories combined), or both.

Check

Verify that the SA and ISSO (at a minimum) are notified in the event of an audit processing failure with the following command:

$ sudo grep '^action_mail_acct' /etc/audit/auditd.conf
action_mail_acct = <administrator_account>

If the value of the "action_mail_acct" keyword is not set to an account for security personnel, the returned line is commented out, or the keyword is missing, this is a finding.

Fix

Configure "auditd" service to notify the SA and ISSO in the event of an audit processing failure.

Edit the following line in "/etc/audit/auditd.conf" to ensure administrators are notified via email for those situations:

action_mail_acct = <administrator_account>

Note: Change "administrator_account" to an account for security personnel.

Restart the "auditd" service so the changes take effect:

$ sudo systemctl restart auditd.service

Ubuntu 24.04 LTS must record time stamps for audit records that can be mapped to Coordinated Universal Time (UTC) or Greenwich Mean Time (GMT).

STIG ID: UBTU-24-901220 | SRG: SRG-OS-000359-GPOS-00146 | Severity: low | CCI: CCI-001890 | Vulnerability Id: V-270820

Vulnerability Discussion

If time stamps are not consistently applied and there is no common time reference, it is difficult to perform forensic analysis.

Time stamps generated by Ubuntu 24.04 LTS include date and time. Time is commonly expressed in Coordinated Universal Time (UTC), a modern continuation of Greenwich Mean Time (GMT), or local time with an offset from UTC.

Check

Verify the time zone is configured to use UTC or GMT with the following command:

$ timedatectl status | grep -i "time zone"
Time zone: UTC (UTC, +0000)

If "Timezone" is not set to UTC or GMT, this is a finding.

Fix

To configure the system time zone to use UTC or GMT, run the following command, replacing [ZONE] with UTC or GMT:

$ sudo timedatectl set-timezone [ZONE]

Ubuntu 24.04 LTS must configure audit tools with a mode of "0755" or less permissive.

STIG ID: UBTU-24-901230 | SRG: SRG-OS-000257-GPOS-00098 | Severity: medium | CCI: CCI-001494,CCI-001493 | Vulnerability Id: V-270821

Vulnerability Discussion

Protecting audit information also includes identifying and protecting the tools used to view and manipulate log data. Therefore, protecting audit tools is necessary to prevent unauthorized operation on audit information.

Operating systems providing tools to interface with audit information will leverage user permissions, roles identifying the user accessing the tools, and the corresponding user rights to make decisions regarding access to audit tools.

Audit tools include, but are not limited to, vendor-provided and open source audit tools needed to successfully view and manipulate audit information system activity and records. Audit tools include custom queries and report generators.

Satisfies: SRG-OS-000257-GPOS-00098, SRG-OS-000256-GPOS-00097

Check

Verify Ubuntu 24.04 LTS configures the audit tools to have a file permission of "0755" or less to prevent unauthorized access with the following command:

$ stat -c "%n %a" /sbin/auditctl /sbin/aureport /sbin/ausearch /sbin/autrace /sbin/auditd /sbin/audispd* /sbin/augenrules
/sbin/auditctl 755
/sbin/aureport 755
/sbin/ausearch 755
/sbin/autrace 755
/sbin/auditd 755
/sbin/audispd 755
/sbin/augenrules 755

If any of the audit tools have a mode more permissive than "0755", this is a finding.

Fix

Configure the audit tools on Ubuntu 24.04 LTS to be protected from unauthorized access by setting the correct permissive mode using the following command:

$ sudo chmod 0755 [audit_tool]

Replace "[audit_tool]" with the audit tool that does not have the correct permissions.

Ubuntu 24.04 LTS must configure audit tools to be owned by root.

STIG ID: UBTU-24-901240 | SRG: SRG-OS-000257-GPOS-00098 | Severity: medium | CCI: CCI-001494,CCI-001493 | Vulnerability Id: V-270822

Vulnerability Discussion

Check

Verify Ubuntu 24.04 LTS configures the audit tools to be owned by root to prevent any unauthorized access with the following command:

$ stat -c "%n %U" /sbin/auditctl /sbin/aureport /sbin/ausearch /sbin/autrace /sbin/auditd /sbin/audispd* /sbin/augenrules
/sbin/auditctl root
/sbin/aureport root
/sbin/ausearch root
/sbin/autrace root
/sbin/auditd root
/sbin/audispd root
/sbin/augenrules root

If any of the audit tools are not owned by root, this is a finding.

Fix

Configure the audit tools on Ubuntu 24.04 LTS to be protected from unauthorized access by setting the file owner as root using the following command:

$ sudo chown root [audit_tool]

Replace "[audit_tool]" with each audit tool not owned by root.

Ubuntu 24.04 LTS must configure the audit tools to be group-owned by root.

STIG ID: UBTU-24-901250 | SRG: SRG-OS-000257-GPOS-00098 | Severity: medium | CCI: CCI-001494,CCI-001493 | Vulnerability Id: V-270823

Vulnerability Discussion

Check

Verify Ubuntu 24.04 LTS configures the audit tools to be group-owned by root to prevent any unauthorized access with the following command:

$ stat -c "%n %G" /sbin/auditctl /sbin/aureport /sbin/ausearch /sbin/autrace /sbin/auditd /sbin/audispd* /sbin/augenrules
/sbin/auditctl root
/sbin/aureport root
/sbin/ausearch root
/sbin/autrace root
/sbin/auditd root
/sbin/audispd root
/sbin/augenrules root

If any of the audit tools are not group-owned by root, this is a finding.

Fix

Configure the audit tools on Ubuntu 24.04 LTS to be protected from unauthorized access by setting the file group as root using the following command:

$ sudo chown :root [audit_tool]

Replace "[audit_tool]" with each audit tool not group-owned by root.

Ubuntu 24.04 LTS must have directories that contain system commands set to a mode of "0755" or less permissive.

STIG ID: UBTU-24-901260 | SRG: SRG-OS-000258-GPOS-00099 | Severity: medium | CCI: CCI-001495 | Vulnerability Id: V-270824

Vulnerability Discussion

Protecting audit information also includes identifying and protecting the tools used to view and manipulate log data. Therefore, protecting audit tools is necessary to prevent unauthorized operation on audit information.

Operating systems providing tools to interface with audit information will leverage user permissions and roles identifying the user accessing the tools and the corresponding rights the user has to make access decisions regarding the deletion of audit tools.

Audit tools include, but are not limited to, vendor-provided and open source audit tools needed to successfully view and manipulate audit information system activity and records. Audit tools include custom queries and report generators.

Check

Verify the system commands directories have mode "0755" or less permissive with the following command:

$ find /bin /sbin /usr/bin /usr/sbin /usr/local/bin /usr/local/sbin -perm /022 -type d -exec stat -c "%n %a" '{}' \;

If any directories are found to be group-writable or world-writable, this is a finding.

Fix

Configure the system commands directories to be protected from unauthorized access. Run the following command:

$ sudo find /bin /sbin /usr/bin /usr/sbin /usr/local/bin /usr/local/sbin -perm /022 -type d -exec chmod -R 755 '{}' \;

Ubuntu 24.04 LTS must have directories that contain system commands owned by root.

STIG ID: UBTU-24-901270 | SRG: SRG-OS-000258-GPOS-00099 | Severity: medium | CCI: CCI-001495 | Vulnerability Id: V-270825

Vulnerability Discussion

Protecting audit information also includes identifying and protecting the tools used to view and manipulate log data. Therefore, protecting audit tools is necessary to prevent unauthorized operation on audit information.

Operating systems providing tools to interface with audit information will leverage user permissions and roles identifying the user accessing the tools and the corresponding rights the user has to make access decisions regarding the deletion of audit tools.

Audit tools include, but are not limited to, vendor-provided and open source audit tools needed to successfully view and manipulate audit information system activity and records. Audit tools include custom queries and report generators.

Check

Verify the system commands directories are owned by root with the following command:

$ sudo find /bin /sbin /usr/bin /usr/sbin /usr/local/bin /usr/local/sbin ! -user root -type d -exec stat -c "%n %U" '{}' \;

If any system commands directories are returned, this is a finding.

Fix

Ubuntu 24.04 LTS must have directories that contain system commands group-owned by root.

STIG ID: UBTU-24-901280 | SRG: SRG-OS-000258-GPOS-00099 | Severity: medium | CCI: CCI-001495 | Vulnerability Id: V-270826

Vulnerability Discussion

Protecting audit information also includes identifying and protecting the tools used to view and manipulate log data. Therefore, protecting audit tools is necessary to prevent unauthorized operation on audit information.

Operating systems providing tools to interface with audit information will leverage user permissions and roles identifying the user accessing the tools and the corresponding rights the user has to make access decisions regarding the deletion of audit tools.

Audit tools include, but are not limited to, vendor-provided and open source audit tools needed to successfully view and manipulate audit information system activity and records. Audit tools include custom queries and report generators.

Check

Verify the system commands directories are group-owned by root with the following command:

$ sudo find /bin /sbin /usr/bin /usr/sbin /usr/local/bin /usr/local/sbin ! -group root -type d -exec stat -c "%n %G" '{}' \;

If any system commands directories are returned that are not Set Group ID up on execution (SGID) files and owned by a privileged account, this is a finding.

Fix

Ubuntu 24.04 LTS must be configured so that audit log files are not read or write-accessible by unauthorized users.

STIG ID: UBTU-24-901300 | SRG: SRG-OS-000057-GPOS-00027 | Severity: medium | CCI: CCI-000162,CCI-000163 | Vulnerability Id: V-270827

Vulnerability Discussion

Check

Verify that the audit log files have a mode of "0600" or less permissive.

Determine where the audit logs are stored with the following command:

$ sudo grep -iw log_file /etc/audit/auditd.conf
log_file = /var/log/audit/audit.log

Using the path of the directory containing the audit logs, determine if the audit log files have a mode of "0600" or less with the following command:

$ sudo stat -c "%n %a" /var/log/audit/*
/var/log/audit/audit.log 600

If the audit log files have a mode more permissive than "0600", this is a finding.

Fix

Configure the audit log files to have a mode of "0600" or less permissive.

Determine where the audit logs are stored with the following command:

$ sudo grep -iw log_file /etc/audit/auditd.conf

log_file = /var/log/audit/audit.log

Using the path of the directory containing the audit logs, configure the audit log files to have a mode of "0600" or less permissive by using the following command:

$ sudo chmod 0600 /var/log/audit/*

Ubuntu 24.04 LTS must be configured to permit only authorized users ownership of the audit log files.

STIG ID: UBTU-24-901310 | SRG: SRG-OS-000057-GPOS-00027 | Severity: medium | CCI: CCI-000162,CCI-000163,CCI-000164 | Vulnerability Id: V-270828

Vulnerability Discussion

Check

Verify the audit log files are owned by "root" account.

Determine where the audit logs are stored with the following command:

$ sudo grep -iw log_file /etc/audit/auditd.conf
log_file = /var/log/audit/audit.log

Using the path of the directory containing the audit logs, determine if the audit log files are owned by the "root" user with the following command:

$ sudo stat -c "%n %U" /var/log/audit/*
/var/log/audit/audit.log root

If the audit log files are owned by a user other than "root", this is a finding.

Fix

Configure the audit log directory and its underlying files to be owned by "root" user.

Determine where the audit logs are stored with the following command:

$ sudo grep -iw log_file /etc/audit/auditd.conf

log_file = /var/log/audit/audit.log

Using the path of the directory containing the audit logs, configure the audit log files to be owned by "root" user by using the following command:

$ sudo chown root /var/log/audit/*

Ubuntu 24.04 LTS must permit only authorized groups ownership of the audit log files.

STIG ID: UBTU-24-901350 | SRG: SRG-OS-000057-GPOS-00027 | Severity: medium | CCI: CCI-000162,CCI-000163,CCI-000164 | Vulnerability Id: V-270829

Vulnerability Discussion

Check

Verify the group owner is set to own newly created audit logs in the audit configuration file with the following command:

$ sudo grep -iw log_group /etc/audit/auditd.conf
log_group = root

If the value of the "log_group" parameter is other than "root", this is a finding.

Determine where the audit logs are stored with the following command:

$ sudo grep -iw log_file /etc/audit/auditd.conf
log_file = /var/log/audit/audit.log

Using the path of the directory containing the audit logs, determine if the audit log files are owned by the "root" group with the following command:

$ sudo stat -c "%n %G" /var/log/audit/*
/var/log/audit/audit.log root

If the audit log files are owned by a group other than "root", this is a finding.

Fix

Configure the audit log directory and its underlying files to be owned by "root" group.

Set the "log_group" parameter of the audit configuration file to the "root" value so when a new log file is created, its group owner is properly set:

$ sudo sed -i '/^log_group/D' /etc/audit/auditd.conf
$ sudo sed -i /^log_file/a'log_group = root' /etc/audit/auditd.conf

Signal the audit daemon to reload the configuration file to update the group owners of existing files:

$ sudo systemctl kill auditd -s SIGHUP

Ubuntu 24.04 LTS must be configured so that the audit log directory is not write-accessible by unauthorized users.

STIG ID: UBTU-24-901380 | SRG: SRG-OS-000059-GPOS-00029 | Severity: medium | CCI: CCI-000164 | Vulnerability Id: V-270830

Vulnerability Discussion

If audit information were to become compromised, then forensic analysis and discovery of the true source of potentially malicious system activity is impossible to achieve.

To ensure the veracity of audit information, Ubuntu 24.04 LTS must protect audit information from unauthorized deletion. This requirement can be achieved through multiple methods, which will depend upon system architecture and design.

Audit information includes all information (e.g., audit records, audit settings, audit reports) needed to successfully audit information system activity.

Check

Verify that the audit log directory has a mode of "0750" or less permissive.

Determine where the audit logs are stored with the following command:

$ sudo grep -iw ^log_file /etc/audit/auditd.conf
log_file = /var/log/audit/audit.log

Using the path of the directory containing the audit logs, determine if the directory has a mode of "0750" or less with the following command:

$ sudo stat -c "%n %a" /var/log/audit
/var/log/audit 750

If the audit log directory has a mode more permissive than "0750", this is a finding.

Fix

Configure the audit log directory to have a mode of "0750" or less permissive.

Determine where the audit logs are stored with the following command:

$ sudo grep -iw ^log_file /etc/audit/auditd.conf

log_file = /var/log/audit/audit.log

Using the path of the directory containing the audit logs, configure the audit log directory to have a mode of "0750" or less permissive by using the following command:

$ sudo chmod -R 750 /var/log/audit

Ubuntu 24.04 LTS must use cryptographic mechanisms to protect the integrity of audit tools.

STIG ID: UBTU-24-90890 | SRG: SRG-OS-000278-GPOS-00108 | Severity: medium | CCI: CCI-001496 | Vulnerability Id: V-270831

Vulnerability Discussion

Protecting the integrity of the tools used for auditing purposes is a critical step toward ensuring the integrity of audit information. Audit information includes all information (e.g., audit records, audit settings, and audit reports) needed to successfully audit information system activity.

Audit tools include, but are not limited to, vendor-provided and open source audit tools needed to successfully view and manipulate audit information system activity and records. Audit tools include custom queries and report generators.

It is not uncommon for attackers to replace the audit tools or inject code into the existing tools with the purpose of providing the capability to hide or erase system activity from the audit logs.

To address this risk, audit tools must be cryptographically signed to provide the capability to identify when the audit tools have been modified, manipulated, or replaced. An example is a checksum hash of the file or files.

Check

Verify that Advanced Intrusion Detection Environment (AIDE) is properly configured to use cryptographic mechanisms to protect the integrity of audit tools with the following command:

$ egrep '(\/sbin\/(audit|au))' /etc/aide/aide.conf
/sbin/auditctl p+i+n+u+g+s+b+acl+xattrs+sha512
/sbin/auditd p+i+n+u+g+s+b+acl+xattrs+sha512
/sbin/ausearch p+i+n+u+g+s+b+acl+xattrs+sha512
/sbin/aureport p+i+n+u+g+s+b+acl+xattrs+sha512
/sbin/autrace p+i+n+u+g+s+b+acl+xattrs+sha512
/sbin/audispd p+i+n+u+g+s+b+acl+xattrs+sha512
/sbin/augenrules p+i+n+u+g+s+b+acl+xattrs+sha512

If any of the seven audit tools do not have appropriate selection lines, this is a finding.

Fix

Add or update the following selection lines for "/etc/aide/aide.conf" to protect the integrity of the audit tools:

# Audit Tools
/sbin/auditctl p+i+n+u+g+s+b+acl+xattrs+sha512
/sbin/auditd p+i+n+u+g+s+b+acl+xattrs+sha512
/sbin/ausearch p+i+n+u+g+s+b+acl+xattrs+sha512
/sbin/aureport p+i+n+u+g+s+b+acl+xattrs+sha512
/sbin/autrace p+i+n+u+g+s+b+acl+xattrs+sha512
/sbin/audispd p+i+n+u+g+s+b+acl+xattrs+sha512
/sbin/augenrules p+i+n+u+g+s+b+acl+xattrs+sha512

Ubuntu 24.04 LTS audit system must protect auditing rules from unauthorized change.

STIG ID: UBTU-24-909000 | SRG: SRG-OS-000058-GPOS-00028 | Severity: medium | CCI: CCI-000163 | Vulnerability Id: V-270832

Vulnerability Discussion

Unauthorized disclosure of audit records can reveal system and configuration data to attackers, thus compromising its confidentiality. Audit information includes all information (e.g., audit records, audit settings, audit reports) needed to successfully audit Ubuntu 24.04 LTS system activity. In immutable mode, unauthorized users cannot execute changes to the audit system to potentially hide malicious activity and then put the audit rules back. A system reboot would be noticeable, and a system administrator could then investigate the unauthorized changes.

Check

Verify the audit system prevents unauthorized changes to the rules with the following command:

$ grep -E '^-e 2' /etc/audit/audit.rules
-e 2

If the audit system is not set to be immutable by adding the "-e 2" option to the end of "/etc/audit/audit.rules", this is a finding.

Fix

Configure the audit system to set the audit rules to be immutable by adding the following line to the end of "/etc/audit/rules.d/audit.rules":

-e 2