Ubuntu 22.04 LTS must store only encrypted representations of passwords.

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.

Verify the Ubuntu operating 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 rounds=100000

If "sha512" is missing from the "pam_unix.so" line, or if the "rounds" is set to less than 100000, this is a finding.

Configure Ubuntu 22.04 LTS to store encrypted representations of passwords.

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 rounds=100000