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 as per policy requirements.

Check

Verify Ubuntu 22.04 LTS prevents passwords from being reused for a minimum of five generations by using the following command:

$ grep -i remember /etc/pam.d/common-password
password [success=1 default=ignore] pam_unix.so obscure sha512 shadow remember=5 rounds=5000

If "remember" is not greater than or equal to "5", is commented out, or is missing, this is a finding.

Fix

Configure Ubuntu 22.04 LTS to prevent passwords from being reused for a minimum of five generations.

Add or modify the following line in the "/etc/pam.d/common-password" file:

password [success=1 default=ignore] pam_unix.so obscure sha512 shadow remember=5 rounds=5000