Title

The audit system must be configured to audit user deletions of files and programs. (Cat III impact)

Discussion

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.

Check Content

To determine if the system is configured to audit user deletions of files and programs, run the following command: $ sudo egrep -w 'rmdir|unlink|unlinkat|rename|renameat' /etc/audit/audit.rules -a always,exit -F arch=b32 -S rmdir -S unlink -S unlinkat -S rename -S renameat -F auid>=500 -F auid!=4294967295 -k delete -a always,exit -F arch=b32 -S rmdir -S unlink -S unlinkat -S rename -S renameat -F auid=0 -k delete -a always,exit -F arch=b64 -S rmdir -S unlink -S unlinkat -S rename -S renameat -F auid>=500 -F auid!=4294967295 -k delete -a always,exit -F arch=b64 -S rmdir -S unlink -S unlinkat -S rename -S renameat -F auid=0 -k delete If the system is 64-bit and does not return rules for both "b32" and "b64" architectures, this is a finding. If the system is not configured to audit "rmdir", this is a finding. If the system is not configured to audit "unlink", this is a finding. If the system is not configured to audit "unlinkat", this is a finding. If the system is not configured to audit "rename", this is a finding. If the system is not configured to audit "renameat", this is a finding. If no line is returned, this is a finding.

Fix Text

At a minimum, the audit system should collect file deletion events for all users and root. Add the following to "/etc/audit/audit.rules": -a always,exit -F arch=b32 -S rmdir -S unlink -S unlinkat -S rename -S renameat -F auid>=500 -F auid!=4294967295 -k delete -a always,exit -F arch=b32 -S rmdir -S unlink -S unlinkat -S rename -S renameat -F auid=0 -k delete If the system is 64-bit, then also add the following: -a always,exit -F arch=b64 -S rmdir -S unlink -S unlinkat -S rename -S renameat -F auid>=500 -F auid!=4294967295 -k delete -a always,exit -F arch=b64 -S rmdir -S unlink -S unlinkat -S rename -S renameat -F auid=0 -k delete

Additional Identifiers

Rule ID: SV-217978r603264_rule

Vulnerability ID: V-217978

Group Title: SRG-OS-000064

Expert Comments

CCIs tied to check.

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