V-22306

Discussion

To ensure password changes are effective in their goals, the system must ensure that old and new passwords have significant differences. Without significant changes, new passwords may be easily guessed based on the value of a previously compromised password.

Check Content

Check /etc/pam.d/common-{auth,account,password,session} for a ‘difok’ parameter on the pam_cracklib.so line. 

Procedure:
# grep difok /etc/pam.d/common-{auth,account,password,session}
If difok is not present, or has a value less than 8, this is a finding.

Check for common-password inclusions.
# grep -c common-password /etc/pam.d/*

If the common-password file is included anywhere
# grep difok /etc/pam.d/common-password 

If common-password is included anywhere and difok is not present, or has a value less than 8, this is a finding.

Ensure the passwd command uses the common-password settings.
# grep common-password /etc/pam.d/passwd
If a line "password include common-password" is not found then the password checks in common-password will not be applied to new passwords and this is a finding.