The delay between login prompts following a failed login attempt must be at least 4 seconds.

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-768	GEN000480	SV-37213r1_rule	ECLO-1 ECLO-2	Medium

Description
Enforcing a delay between successive failed login attempts increases protection against automated password guessing attacks.

STIG	Date
Red Hat Enterprise Linux 5 Security Technical Implementation Guide	2013-01-17

Details

Check Text ( C-35903r2_chk )
Check the value of the FAIL_DELAY variable and the ability to use it. Procedure: # grep FAIL_DELAY /etc/login.defs If the value does not exist, or is less than 4, this is a finding. Check for the use of pam_faildelay. # grep pam_faildelay /etc/pam.d/system-auth* If pam_faildelay.so module is not present, this is a finding. If pam_faildelay is present only in /etc/pam.d/system-auth-ac: ensure that /etc/pam.d/system-auth includes /etc/pam.d/system-auth-ac. #grep system-auth-ac /etc/pam.d/system-auth This should return: auth include system-auth-ac account include system-auth-ac password include system-auth-ac session include system-auth-ac /etc/pam.d/system-auth-ac should only be included by /etc/pam.d/system-auth. All other pam files should include /etc/pam.d/system-auth. If pam_faildelay is not defined in /etc/pam.d/system-auth either directly or through inclusion of system-auth-ac, this is a finding.

Check Text ( C-35903r2_chk )

Check the value of the FAIL_DELAY variable and the ability to use it.

Procedure:
# grep FAIL_DELAY /etc/login.defs
If the value does not exist, or is less than 4, this is a finding.

Check for the use of pam_faildelay.
# grep pam_faildelay /etc/pam.d/system-auth*
If pam_faildelay.so module is not present, this is a finding.

If pam_faildelay is present only in /etc/pam.d/system-auth-ac:
ensure that /etc/pam.d/system-auth includes /etc/pam.d/system-auth-ac.
#grep system-auth-ac /etc/pam.d/system-auth

This should return:
auth include system-auth-ac
account include system-auth-ac
password include system-auth-ac
session include system-auth-ac

/etc/pam.d/system-auth-ac should only be included by /etc/pam.d/system-auth. All other pam files should include /etc/pam.d/system-auth.

If pam_faildelay is not defined in /etc/pam.d/system-auth either directly or through inclusion of system-auth-ac, this is a finding.

Fix Text (F-31161r1_fix)
Add the pam_faildelay module and set the FAIL_DELAY variable. Procedure: Edit /etc/login.defs and set the value of the FAIL_DELAY variable to 4 or more. The default link /etc/pam.d/system-auth points to /etc/pam.d/system-auth-ac which is the file maintained by the authconfig utility. In order to add pam options other than those available via the utility create or modify /etc/pam.d/system-auth-local with the options and including system-auth-ac. For example: auth required pam_access.so auth optional pam_faildelay.so delay=4000000 auth include system-auth-ac account include system-auth-ac password include system-auth-ac session include system-auth-ac Once system-auth-local is written ensure the /etc/pam.d/system-auth points to system-auth-local. This is necessary because authconfig writes directly to system-auth-ac so any manual changes made will be lost if authconfig is run.

Fix Text (F-31161r1_fix)

Add the pam_faildelay module and set the FAIL_DELAY variable.

Procedure:

Edit /etc/login.defs and set the value of the FAIL_DELAY variable to 4 or more.

The default link /etc/pam.d/system-auth points to /etc/pam.d/system-auth-ac which is the file maintained by the authconfig utility. In order to add pam options other than those available via the utility create or modify /etc/pam.d/system-auth-local with the options and including system-auth-ac. For example:

auth required pam_access.so
auth optional pam_faildelay.so delay=4000000
auth include system-auth-ac
account include system-auth-ac
password include system-auth-ac
session include system-auth-ac

Once system-auth-local is written ensure the /etc/pam.d/system-auth points to system-auth-local. This is necessary because authconfig writes directly to system-auth-ac so any manual changes made will be lost if authconfig is run.