Ubuntu OS must enforce a minimum 15-character password length.

The shorter the password, the lower the number of possible combinations that need to be tested before the password is compromised.

Password complexity, or strength, is a measure of the effectiveness of a password in resisting attempts at guessing and brute-force attacks. Password length is one factor of several that helps to determine strength and how long it takes to crack a password. Use of more characters in a password helps to exponentially increase the time and/or resources required to compromise the password.

Verify with the following command that the pwquality configuration file enforces a minimum 15-character password length:

     $ grep -i minlen /etc/security/pwquality.conf 
     minlen = 15 

If "minlen" is not "15" or higher, is commented out, or is missing, this is a finding.

Configure Ubuntu OS to enforce a minimum 15-character password length.

Add or modify the following line in the "/etc/security/pwquality.conf" file:

minlen = 15