Ubuntu OS must have the "libpam-pwquality" package installed.

Use of a complex password helps to increase the time and resources required to compromise the password. Password complexity, or strength, is a measure of the effectiveness of a password in resisting attempts at guessing and brute-force attacks. "pwquality" enforces complex password construction configuration and has the ability to limit brute-force attacks on the system.

Verify Ubuntu OS has the "libpam-pwquality" package installed with the following command:

     $ dpkg -l | grep libpam-pwquality 
     ii     libpam-pwquality:amd64     1.4.4-1build2     amd64     PAM module to check password strength 

If "libpam-pwquality" is not installed, this is a finding.

Install the "pam_pwquality" package by using the following command:

     $ sudo apt-get install libpam-pwquality