All uses of the unlink command must be audited.

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-72205	RHEL-07-030910	SV-86829r2_rule		Medium

Description
If the system is not configured to audit certain activities and write them to an audit log, it is more difficult to detect and track system compromises and damages incurred during a system compromise. Satisfies: SRG-OS-000466-GPOS-00210, SRG-OS-000467-GPOS-00210, SRG-OS-000468-GPOS-00212, SRG-OS-000392-GPOS-00172

STIG	Date
Red Hat Enterprise Linux 7 Security Technical Implementation Guide	2017-07-08

Details

Check Text ( C-72439r3_chk )
Verify the operating system generates audit records when successful/unsuccessful attempts to use the "unlink" command occur. Check the file system rules in "/etc/audit/audit.rules" with the following commands: Note: The output lines of the command are duplicated to cover both 32-bit and 64-bit architectures. Only the lines appropriate for the system architecture must be present. # grep -i unlink/etc/audit/audit.rules -a always,exit -F arch=b32 -S unlink -F perm=x -F auid>=1000 -F auid!=4294967295 -k delete -a always,exit -F arch=b64 -S unlink -F perm=x -F auid>=1000 -F auid!=4294967295 -k delete If the command does not return any output, this is a finding.

Check Text ( C-72439r3_chk )

Verify the operating system generates audit records when successful/unsuccessful attempts to use the "unlink" command occur.

Check the file system rules in "/etc/audit/audit.rules" with the following commands:

Note: The output lines of the command are duplicated to cover both 32-bit and 64-bit architectures. Only the lines appropriate for the system architecture must be present.

# grep -i unlink/etc/audit/audit.rules
-a always,exit -F arch=b32 -S unlink -F perm=x -F auid>=1000 -F auid!=4294967295 -k delete
-a always,exit -F arch=b64 -S unlink -F perm=x -F auid>=1000 -F auid!=4294967295 -k delete

If the command does not return any output, this is a finding.

Fix Text (F-78559r4_fix)
Configure the operating system to generate audit records when successful/unsuccessful attempts to use the "unlink" command occur. Add the following rules in "/etc/audit/rules.d/audit.rules" (removing those that do not match the CPU architecture): -a always,exit -F arch=b32 -S unlink -F perm=x -F auid>=1000 -F auid!=4294967295 -k delete -a always,exit -F arch=b64 -S unlink -F perm=x -F auid>=1000 -F auid!=4294967295 -k delete The audit daemon must be restarted for the changes to take effect.

Fix Text (F-78559r4_fix)

Configure the operating system to generate audit records when successful/unsuccessful attempts to use the "unlink" command occur.

Add the following rules in "/etc/audit/rules.d/audit.rules" (removing those that do not match the CPU architecture):

-a always,exit -F arch=b32 -S unlink -F perm=x -F auid>=1000 -F auid!=4294967295 -k delete
-a always,exit -F arch=b64 -S unlink -F perm=x -F auid>=1000 -F auid!=4294967295 -k delete

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