5.3.2 Ensure lockout for failed password attempts is configured - system-auth 'auth required pam_faillock.so preauth audit silent deny=5 unlock_time=900'

Information

Lock out users after n unsuccessful consecutive login attempts. The first sets of changes are made to the PAM configuration files. The second set of changes are applied to the program specific PAM configuration file. The second set of changes must be applied to each program that will lock out users. Check the documentation for each secondary program for instructions on how to configure them to work with PAM.

Set the lockout number to the policy in effect at your site.

Rationale:

Locking out user IDs after n unsuccessful consecutive login attempts mitigates brute force password attacks against your systems.

Solution

Edit the /etc/pam.d/password-auth and /etc/pam.d/system-auth files and add the following pam_faillock.so lines surrounding a pam_unix.so line modify the pam_unix.so is [success=1 default=bad] as listed in both:

auth required pam_faillock.so preauth audit silent deny=5 unlock_time=900
auth [success=1 default=bad] pam_unix.so
auth [default=die] pam_faillock.so authfail audit deny=5 unlock_time=900
auth sufficient pam_faillock.so authsucc audit deny=5 unlock_time=900




Notes:

Consult your documentation for the appropriate PAM file and module.

Additional module options may be set, recommendation only covers those listed here.

If a user has been locked out because they have reached the maximum consecutive failure count defined by deny= in the pam_tally2.so or pam_faillock.so module, the user can be unlocked by issuing the command pam_tally2 -u <username> --reset or faillock -u --reset respectively. This command sets the failed count to 0, effectively unlocking the user.

Use of the 'audit' keyword may log credentials in the case of user error during authentication. This risk should be evaluated in the context of the site policies of your organization.

This Benchmark recommendation maps to:

Red Hat Enterprise Linux 7 Security Technical Implementation Guide:

Version 2, Release: 3 Benchmark Date: 26 Apr 2019



Vul ID: V-71943

Rule ID: SV-86567r4_rule

STIG ID: RHEL-07-010320

Severity: CAT II

See Also

https://workbench.cisecurity.org/files/2688

Item Details

Category: CONFIGURATION MANAGEMENT

References: 800-53|CM-6, CSCv7|5.1

Plugin: Unix

Control ID: 9bd5ed61e38274d5dd81d18182748f294dbf178f4e6de06785f7e7edade5d9fa