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Successful/unsuccessful uses of the chmod command in RHEL 8 must generate an audit record.


Overview

Finding ID Version Rule ID IA Controls Severity
V-230456 RHEL-08-030490 SV-230456r627750_rule Medium
Description
Without generating audit records that are specific to the security and mission needs of the organization, it would be difficult to establish, correlate, and investigate the events relating to an incident or identify those responsible for one. Audit records can be generated from various components within the information system (e.g., module or policy filter). The "chmod" command changes the file mode bits of each given file according to mode, which can be either a symbolic representation of changes to make, or an octal number representing the bit pattern for the new mode bits. 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, SRG-OS-000064-GPOS-00033, SRG-OS-000466-GPOS-00210
STIG Date
Red Hat Enterprise Linux 8 Security Technical Implementation Guide 2021-03-04

Details

Check Text ( C-33125r568114_chk )
Verify RHEL 8 generates an audit record when successful/unsuccessful attempts to use the "chmod" command by performing the following command to check the file system rules in "/etc/audit/audit.rules":

$ sudo grep -w chmod /etc/audit/audit.rules

-a always,exit -F arch=b32 -S chmod -F auid>=1000 -F auid!=unset -k perm_mod
-a always,exit -F arch=b64 -S chmod -F auid>=1000 -F auid!=unset -k perm_mod

If the command does not return a line, or the line is commented out, this is a finding.
Fix Text (F-33100r568115_fix)
Configure the audit system to generate an audit event for any successful/unsuccessful use of the "chmod" command by adding or updating the following line to "/etc/audit/rules.d/audit.rules":

-a always,exit -F arch=b32 -S chmod -F auid>=1000 -F auid!=unset -k perm_mod
-a always,exit -F arch=b64 -S chmod -F auid>=1000 -F auid!=unset -k perm_mod

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