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

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-51137	OL6-00-000200	SV-65347r1_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
Oracle Linux 6 Security Technical Implementation Guide	2014-06-12

Details

Check Text ( C-53539r1_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 unlink \| grep -v unlinkat If the system is configured to audit this activity, it will return several lines. To determine if the system is configured to audit calls to the "unlinkat" system call, run the following command: # auditctl -l \| grep syscall \| grep unlinkat If the system is configured to audit this activity, it will return several lines. To determine if the system is configured to audit calls to the "rename" system call, run the following command: # auditctl -l \| grep syscall \| grep rename \| grep -v renameat If the system is configured to audit this activity, it will return several lines. To determine if the system is configured to audit calls to the "renameat" system call, run the following command: # auditctl -l \| grep syscall \| grep renameat If the system is configured to audit this activity, it will return several lines. If no line is returned, this is a finding.

Check Text ( C-53539r1_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 unlink | grep -v unlinkat

If the system is configured to audit this activity, it will return several lines.

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

# auditctl -l | grep syscall | grep unlinkat

If the system is configured to audit this activity, it will return several lines. To determine if the system is configured to audit calls to the "rename" system call, run the following command:

# auditctl -l | grep syscall | grep rename | grep -v renameat

If the system is configured to audit this activity, it will return several lines. To determine if the system is configured to audit calls to the "renameat" system call, run the following command:

# auditctl -l | grep syscall | grep renameat

If the system is configured to audit this activity, it will return several lines.

If no line is returned, this is a finding.

Fix Text (F-55945r1_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-55945r1_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