Title

SLEM 5 must require the change of at least eight of the total number of characters when passwords are changed. (Cat II impact)

Discussion

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.

Check Content

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.

Fix Text

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.

Additional Identifiers

Rule ID: SV-261383r996580_rule

Vulnerability ID: V-261383

Group Title: SRG-OS-000072-GPOS-00040

Expert Comments

CCIs tied to check.

Controls tied to check. These are derived from the CCIs shown above.