SLEM 5 must require the change of at least eight of the total number of characters when passwords are changed.

If SLEM 5 allows the user to consecutively reuse extensive portions of passwords, this increases the chances of password compromise by increasing the window of opportunity for attempts at guessing and brute-force attacks.

Verify SLEM 5 requires at least eight characters be changed between the old and new passwords during a password change with the following command:

     > grep pam_cracklib.so /etc/pam.d/common-password
     password requisite pam_cracklib.so difok=8

If the value for "difok" is not "8" or greater, if "difok" is missing from the line, the second column value different from "requisite", the line is commented out, or the line is missing, this is a finding.

Configure SLEM 5 to require at least eight characters be changed between the old and new passwords during a password change with the following command:

Edit "/etc/pam.d/common-password" and edit the line containing "pam_cracklib.so" to contain the option "difok=8" after the third column.