Vulnerability Discussion

If security personnel are not notified immediately when storage volume reaches 75% utilization, they are unable to plan for audit record storage capacity expansion.

Check

Verify the Ubuntu operating system notifies the SA and ISSO (at a minimum) when allocated audit record storage volume reaches 75% of the repository maximum audit record storage capacity with the following command:

$ 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 missing, set to blanks, or set to a value less than 25% 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 "syslog", the system logs the event but does not generate a notification, and 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.

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.

Note: If the email address of the System Administrator
is on a remote system, a mail package must be available.

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% of the repository maximum audit record storage capacity.