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. The "maxclassrepeat" option sets the maximum number of allowed same consecutive characters in the same class in the new password.

Check

Check for the value of the "maxclassrepeat" option with the following command:

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

/etc/security/pwquality.conf:maxclassrepeat = 4

If the value of "maxclassrepeat" is set to "0", more than "4" or is commented out, this is a finding.
If conflicting results are returned, this is a finding.

Fix

Configure the operating system to require the change of the number of repeating characters of the same character class when passwords are changed by setting the "maxclassrepeat" option.

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

maxclassrepeat = 4

Remove any configurations that conflict with the above value.