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