Vulnerability Discussion

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.

RHEL 8 utilizes pwquality as a mechanism to enforce password complexity. Note that in order to require lower-case characters without degrading the "minlen" value, the credit value must be expressed as a negative number in "/etc/security/pwquality.conf".

Check

Verify the value for "lcredit" with the following command:

$ sudo grep -r lcredit /etc/security/pwquality.conf*

/etc/security/pwquality.conf:lcredit = -1

If the value of "lcredit" is a positive number or is commented out, this is a finding.
If conflicting results are returned, this is a finding.

Fix

Configure the operating system to enforce password complexity by requiring that at least one lower-case character be used by setting the "lcredit" option.

Add the following line to /etc/security/pwquality.conf (or modify the line to have the required value):

lcredit = -1

Remove any configurations that conflict with the above value.