OL 9 must be configured so that successful/unsuccessful uses of the umount system call generate an audit record.

Severity	Group ID	Group Title	Version	Rule ID	Date	STIG Version
medium	V-271594	SRG-OS-000037-GPOS-00015	OL09-00-000840	SV-271594r1155314_rule	2025-12-22	1

Description
The changing of file permissions could indicate that a user is attempting to gain access to information that would otherwise be disallowed. Auditing DAC modifications can facilitate the identification of patterns of abuse among both authorized and unauthorized users. Satisfies: SRG-OS-000037-GPOS-00015, SRG-OS-000062-GPOS-00031, SRG-OS-000392-GPOS-00172, SRG-OS-000462-GPOS-00206, SRG-OS-000471-GPOS-00215

Description

The changing of file permissions could indicate that a user is attempting to gain access to information that would otherwise be disallowed. Auditing DAC modifications can facilitate the identification of patterns of abuse among both authorized and unauthorized users. Satisfies: SRG-OS-000037-GPOS-00015, SRG-OS-000062-GPOS-00031, SRG-OS-000392-GPOS-00172, SRG-OS-000462-GPOS-00206, SRG-OS-000471-GPOS-00215

ℹ️ Check
Verify OL 9 is configured to audit the execution of the "umount" command with the following command: $ sudo auditctl -l \| grep umount -a always,exit -F arch=b32 -S umount -F auid>=1000 -F auid!=-1 -F key=privileged-umount If the command does not return an audit rule for "umount" or any of the lines returned are commented out, this is a finding.

✔️ Fix
Configure the audit system to generate an audit event for any successful/unsuccessful use of the umount system call by adding or updating the following rules in "/etc/audit/audit.rules" and adding the following rules to "/etc/audit/rules.d/perm_mod.rules" or updating the existing rules in files in the "/etc/audit/rules.d/" directory: -a always,exit -F arch=b32 -S umount -F auid>=1000 -F auid!=unset -k perm_mod -a always,exit -F arch=b64 -S umount -F auid>=1000 -F auid!=unset -k perm_mod The audit daemon must be restarted for the changes to take effect. Restart auditd: $ sudo service auditd restart

✔️ Fix

Configure the audit system to generate an audit event for any successful/unsuccessful use of the umount system call by adding or updating the following rules in "/etc/audit/audit.rules" and adding the following rules to "/etc/audit/rules.d/perm_mod.rules" or updating the existing rules in files in the "/etc/audit/rules.d/" directory: -a always,exit -F arch=b32 -S umount -F auid>=1000 -F auid!=unset -k perm_mod -a always,exit -F arch=b64 -S umount -F auid>=1000 -F auid!=unset -k perm_mod The audit daemon must be restarted for the changes to take effect. Restart auditd: $ sudo service auditd restart