SLEM 5 must not allow passwords to be reused for a minimum of five generations.

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 as per policy requirements.

Verify SLEM 5 prohibits the reuse of a password for a minimum of five generations with the following command:

     > grep pam_pwhistory.so /etc/pam.d/common-password
     password requisite pam_pwhistory.so remember=5 use_authtok

If the value for "remember" is not "5" or greater, if the "remember" option is missing from the line, if the "use_authtok" option is missing, if the second column has a value different from "requisite", if the line is commented out, or the line is missing, this is a finding.

Configure SLEM 5 password history to prohibit the reuse of a password for a minimum of five generations.

Edit "/etc/pam.d/common-password" and edit the line containing "pam_pwhistory.so" to contain the option "remember=5 use_authtok" after the third column.