Vulnerability Discussion

Password complexity, or strength, is a measure of the effectiveness of a password in resisting attempts at guessing and brute-force attacks. If the information system or application allows the user to consecutively reuse their password when that password has exceeded its defined lifetime, the end result is a password that is not changed per policy requirements.

Check

Verify the operating system prohibits password reuse for a minimum of five generations.

Check for the value of the "remember" argument in "/etc/pam.d/system-auth" and "/etc/pam.d/password-auth" with the following command:

# grep -i remember /etc/pam.d/system-auth /etc/pam.d/password-auth
password requisite pam_pwhistory.so use_authtok remember=5 retry=3

If the line containing the "pam_pwhistory.so" line does not have the "remember" module argument set, is commented out, or the value of the "remember" module argument is set to less than "5", this is a finding.

Fix

Configure the operating system to prohibit password reuse for a minimum of five generations.

Add the following line in "/etc/pam.d/system-auth" and "/etc/pam.d/password-auth" (or modify the line to have the required value):

password requisite pam_pwhistory.so use_authtok remember=5 retry=3

Note: Per requirement RHEL-07-010199, RHEL 7 must be configured to not overwrite custom authentication configuration settings while using the authconfig utility, otherwise manual changes to the listed files will be overwritten whenever the authconfig utility is used.