The shorter the password, the lower the number of possible combinations that must 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 increase exponentially the time and/or resources required to compromise the password.
RHEL 10 uses "pwquality" as a mechanism to enforce password complexity. Configurations are set in the "etc/security/pwquality.conf" file.
The "minlen", sometimes noted as minimum length, acts as a "score" of complexity based on the credit components of the "pwquality" module. By setting the credit components to a negative value, those components will not only be required but will not count toward the total "score" of "minlen". This will enable "minlen" to require a 15-character minimum.
The DOD minimum password requirement is 15 characters.
Check
Verify RHEL 10 enforces a minimum 15-character password length with the following command:
If the command does not return a "minlen" value of "15" or greater, does not return a line, or the line is commented out, this is a finding.
Fix
Configure RHEL 10 to enforce a minimum 15-character password length.
Add or update the following line in the "/etc/security/pwquality.conf" file or a configuration file in the "/etc/security/pwquality.conf.d/" directory to contain the "minlen" parameter: