The audit system must be configured to audit user deletions of files and programs.

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-38575	RHEL-06-000200	SV-50376r3_rule		Low

Description
Auditing file deletions will create an audit trail for files that are removed from the system. The audit trail could aid in system troubleshooting, as well as detecting malicious processes that attempt to delete log files to conceal their presence.

STIG	Date
Red Hat Enterprise Linux 6 Security Technical Implementation Guide	2014-06-11

Details

Check Text ( C-46133r2_chk )
To determine if the system is configured to audit calls to the "unlink" system call, run the following command: # auditctl -l \| grep syscall \| grep -w unlink If the system is configured to audit this activity, it will return a line. To determine if the system is configured to audit calls to the "unlinkat" system call, run the following command: # auditctl -l \| grep syscall \| grep -w unlinkat If the system is configured to audit this activity, it will return a line. To determine if the system is configured to audit calls to the "rename" system call, run the following command: # auditctl -l \| grep syscall \| grep -w rename If the system is configured to audit this activity, it will return a line. To determine if the system is configured to audit calls to the "renameat" system call, run the following command: # auditctl -l \| grep syscall \| grep -w renameat If the system is configured to audit this activity, it will return a line. If no line is returned, this is a finding.

Check Text ( C-46133r2_chk )

To determine if the system is configured to audit calls to the "unlink" system call, run the following command:

# auditctl -l | grep syscall | grep -w unlink

If the system is configured to audit this activity, it will return a line.

To determine if the system is configured to audit calls to the "unlinkat" system call, run the following command:

# auditctl -l | grep syscall | grep -w unlinkat

If the system is configured to audit this activity, it will return a line.

To determine if the system is configured to audit calls to the "rename" system call, run the following command:

# auditctl -l | grep syscall | grep -w rename

If the system is configured to audit this activity, it will return a line.

To determine if the system is configured to audit calls to the "renameat" system call, run the following command:

# auditctl -l | grep syscall | grep -w renameat

If the system is configured to audit this activity, it will return a line.

If no line is returned, this is a finding.

Fix Text (F-43523r2_fix)
At a minimum, the audit system should collect file deletion events for all users and root. Add the following to "/etc/audit/audit.rules", setting ARCH to either b32 or b64 as appropriate for your system: -a always,exit -F arch=ARCH -S unlink -S unlinkat -S rename -S renameat \ -F auid>=500 -F auid!=4294967295 -k delete -a always,exit -F arch=ARCH -S unlink -S unlinkat -S rename -S renameat \ -F auid=0 -k delete

Fix Text (F-43523r2_fix)

At a minimum, the audit system should collect file deletion events for all users and root. Add the following to "/etc/audit/audit.rules", setting ARCH to either b32 or b64 as appropriate for your system:

-a always,exit -F arch=ARCH -S unlink -S unlinkat -S rename -S renameat \
-F auid>=500 -F auid!=4294967295 -k delete
-a always,exit -F arch=ARCH -S unlink -S unlinkat -S rename -S renameat \
-F auid=0 -k delete