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Successful/unsuccessful uses of unix_chkpwd in RHEL 8 must generate an audit record.


Overview

Finding ID Version Rule ID IA Controls Severity
V-230433 RHEL-08-030317 SV-230433r627750_rule Medium
Description
Reconstruction of harmful events or forensic analysis is not possible if audit records do not contain enough information. At a minimum, the organization must audit the full-text recording of privileged commands. The organization must maintain audit trails in sufficient detail to reconstruct events to determine the cause and impact of compromise. The "unix_chkpwd" command is a helper program for the pam_unix module that verifies the password of the current user. It also checks password and account expiration dates in shadow. It is not intended to be run directly from the command line and logs a security violation if done so. When a user logs on, the AUID is set to the UID of the account that is being authenticated. Daemons are not user sessions and have the loginuid set to "-1". The AUID representation is an unsigned 32-bit integer, which equals "4294967295". The audit system interprets "-1", "4294967295", and "unset" in the same way. Satisfies: SRG-OS-000062-GPOS-00031, SRG-OS-000037-GPOS-00015, SRG-OS-000042-GPOS-00020, SRG-OS-000062-GPOS-00031, SRG-OS-000392-GPOS-00172, SRG-OS-000462-GPOS-00206, SRG-OS-000471-GPOS-00215
STIG Date
Red Hat Enterprise Linux 8 Security Technical Implementation Guide 2022-09-07

Details

Check Text ( C-33102r568045_chk )
Verify that an audit event is generated for any successful/unsuccessful use of "unix_chkpwd" by performing the following command to check the file system rules in "/etc/audit/audit.rules":

$ sudo grep -w "unix_chkpwd" /etc/audit/audit.rules

-a always,exit -F path=/usr/sbin/unix_chkpwd -F perm=x -F auid>=1000 -F auid!=unset -k privileged-unix-update

If the command does not return a line, or the line is commented out, this is a finding.
Fix Text (F-33077r568046_fix)
Configure the audit system to generate an audit event for any successful/unsuccessful uses of the "unix_chkpwd" by adding or updating the following rule in the "/etc/audit/rules.d/audit.rules" file:

-a always,exit -F path=/usr/sbin/unix_chkpwd -F perm=x -F auid>=1000 -F auid!=unset -k privileged-unix-update

The audit daemon must be restarted for the changes to take effect.