Vulnerability Discussion

Restricting TFTP to a specific directory prevents remote users from copying, transferring, or overwriting system files.

Check

Note: If a TFTP server is not installed, this rule is not applicable.

Verify RHEL 10 is configured to operate in secure mode if the TFTP server service is required.

Determine if the TFTP server is installed with the following command:

$ sudo dnf list installed | grep tftp-server
tftp-server.x86_64 5.2-48.el10 @rhel-10-for-x86_64-appstream-rpms

Verify that the TFTP daemon, if "tftp.server" is installed, is configured to operate in secure mode with the following command:

$ systemctl cat tftp.service | grep -i execstart
ExecStart=/usr/sbin/in.tftpd -s /var/lib/tftpboot

Note: The "-s" option ensures that the TFTP server serves only files from the specified directory, which is a security measure to prevent unauthorized access to other parts of the file system.

If the TFTP server is installed, but the TFTP daemon is not configured to operate in secure mode, and tftp is not documented as critical to the mission with the information system security officer, this is a finding.

Fix

Configure RHEL 10 TFTP to operate in secure mode with the following command:

$ sudo systemctl edit tftp.service

In the editor, enter the following:

[Service]
ExecStart=/usr/sbin/in.tftpd -s /var/lib/tftpboot

After making changes, reload the systemd daemon and restart the TFTP service as follows:

$ sudo systemctl daemon-reload
$ sudo systemctl restart tftp.service