Rule ID
SV-253001r958412_rule
Version
V2R5
Without generating audit records that are specific to the security and mission needs of the organization, it would be difficult to establish, correlate, and investigate the events relating to an incident or identify those responsible for one. Audit records can be generated from various components within the information system (e.g., module or policy filter). The "unlinkat" system call operates in exactly the same way as either "unlink" or "rmdir" except for the differences described in the manual page. When a user logs on, the AUID is set to the UID of the account that is being authenticated. Daemons are not user sessions and have the loginuid set to "-1." The AUID representation is an unsigned 32-bit integer, which equals "4294967295." The audit system interprets "-1", "4294967295", and "unset" in the same way. Satisfies: SRG-OS-000037-GPOS-00015, SRG-OS-000042-GPOS-00020, SRG-OS-000062-GPOS-00031, SRG-OS-000392-GPOS-00172, SRG-OS-000462-GPOS-00206, SRG-OS-000468-GPOS-00212, SRG-OS-000471-GPOS-00215
Verify that an audit event is generated for any successful/unsuccessful use of the "unlinkat" command by performing the following command to check the file system rules in "/etc/audit/audit.rules": $ sudo grep -w "unlinkat" /etc/audit/audit.rules -a always,exit -F arch=b32 -S unlinkat -F auid>=1000 -F auid!=unset -k delete -a always,exit -F arch=b64 -S unlinkat -F auid>=1000 -F auid!=unset -k delete If the command does not return a line, or the line is commented out, this is a finding.
Configure the audit system to generate an audit event for any successful/unsuccessful use of the "unlinkat" syscall by adding or updating the following rules in the "/etc/audit/rules.d/audit.rules" file: -a always,exit -F arch=b32 -S unlinkat -F auid>=1000 -F auid!=unset -k delete -a always,exit -F arch=b64 -S unlinkat -F auid>=1000 -F auid!=unset -k delete The audit daemon must be restarted for the changes to take effect.