The system must prohibit the reuse of passwords within five iterations.

From Red Hat Enterprise Linux 6 Security Technical Implementation Guide

Associated with: CCI-000200

SV-50459r5_rule The system must prohibit the reuse of passwords within five iterations.

Vulnerability discussion

Preventing reuse of previous passwords helps ensure that a compromised password is not reused by a user.

Check content

To verify the password reuse setting is compliant, run the following command: # grep remember /etc/pam.d/system-auth The output must be a line beginning with "password required pam_pwhistory.so" or "password requisite pam_pwhistory.so" and end with "remember=5". If the line is commented out, the line does not contain the specified elements, or the value for "remember" is less than 5, this is a finding.

Fix text

Do not allow users to reuse recent passwords. This can be accomplished by using the "remember" option for the "pam_pwhistory" PAM module. In the file "/etc/pam.d/system-auth", append "remember=5" to the line which refers to the "pam_pwhistory.so" module, as shown: password required pam_pwhistory.so [existing_options] remember=5 or password requisite pam_pwhistory.so [existing_options] remember=5 The DoD requirement is five passwords.

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