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

Severity	Group ID	Group Title	Version	Rule ID	Date	STIG Version
medium	V-261383	SRG-OS-000072-GPOS-00040	SLEM-05-611040	SV-261383r996580_rule	2024-06-04	1

Description
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.

ℹ️ Check
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.

ℹ️ Check

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
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.