Ubuntu OS must enforce password complexity by requiring at least one numeric character be used.

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.

Password complexity is one factor of several that determines how long it takes to crack a password. The more complex the password, the greater the number of possible combinations that need to be tested before the password is compromised.

Verify with the following command that Ubuntu OS enforces password complexity by requiring at least one numeric character be used:

     $ grep -i dcredit /etc/security/pwquality.conf 
     dcredit = -1  

If "dcredit" is greater than "-1", is commented out, or is missing, this is a finding.

Configure Ubuntu OS to enforce password complexity by requiring at least one numeric character be used.

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

dcredit = -1