Successful/unsuccessful uses of the fchmodat system call in TOSS must generate an audit record.
An XCCDF Rule
Description
<VulnDiscussion>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 "fchmodat" system call is used to change permissions of a file relative to a directory file descriptor. 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-000064-GPOS-00033, SRG-OS-000462-GPOS-00206</VulnDiscussion><FalsePositives></FalsePositives><FalseNegatives></FalseNegatives><Documentable>false</Documentable><Mitigations></Mitigations><SeverityOverrideGuidance></SeverityOverrideGuidance><PotentialImpacts></PotentialImpacts><ThirdPartyTools></ThirdPartyTools><MitigationControl></MitigationControl><Responsibility></Responsibility><IAControls></IAControls>
- ID
- SV-253013r958446_rule
- Severity
- Medium
- References
- Updated
Remediation - Manual Procedure
Configure the audit system to generate an audit event for any successful/unsuccessful use of the "fchmodat" system call by adding or updating the following lines to "/etc/audit/rules.d/audit.rules":
-a always,exit -F arch=b32 -S fchmodat -F auid>=1000 -F auid!=unset -k perm_mod
-a always,exit -F arch=b64 -S fchmodat -F auid>=1000 -F auid!=unset -k perm_mod
The audit daemon must be restarted for the changes to take effect.