Vulnerability Discussion

Providing users with feedback on when account accesses via SSH last occurred facilitates user recognition and reporting of unauthorized account use.

Check

Verify SSH provides users with feedback on when account accesses last occurred with the following command:

$ sudo /usr/sbin/sshd -dd 2>&1 | awk '/filename/ {print $4}' | tr -d '\r' | tr '\n' ' ' | xargs sudo grep -iH '^\s*printlastlog'

PrintLastLog yes

If the "PrintLastLog" keyword is set to "no", is missing, or is commented out, this is a finding.

If conflicting results are returned, this is a finding.

Fix

Configure SSH to provide users with feedback on when account accesses last occurred by setting the required configuration options in "/etc/pam.d/sshd" or in the "sshd_config" file used by the system ("/etc/ssh/sshd_config" will be used in the example) (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).

Modify the "PrintLastLog" line in "/etc/ssh/sshd_config" to match the following:

PrintLastLog yes

The SSH service must be restarted for changes to "sshd_config" to take effect.