AC-24 Access Control Decisions. [organization-defined] to ensure [organization-defined] are applied to each access request prior to access enforcement
Access Control Decisions. [organization-defined] to ensure [organization-defined] are applied to each access request prior to access enforcement.
5
artefacts
0
held by a system
2
at each review
hard
to go live
Policy repository / GRC workspace
where the evidence lives
teal = a system already holds it · olive = produced at each review
system holds itEvidence a system already holds
none for this control
periodic reviewEvidence produced at each review
- Audit records of access decisions showing the decision outcome and the inputs that produced it · Identity provider / directory
- Evidence that enforcement points cannot grant access without a decision, including on failure of the decision service · Identity provider / directory
governing documentDocuments that govern the control
- Documented access control decision procedure showing the decision is reached before enforcement, not after · Policy repository / GRC workspace
- Design documentation identifying the policy decision point and the policy enforcement points it serves · Policy repository / GRC workspace
- The attributes and policies the decision uses, and where they are sourced at decision time · Policy repository / GRC workspace
First move
This control is evidenced by people and documents, not systems. Put the document under version control with an owner and review date, and log each review as a record with reviewer and date. Do not try to automate it.
Common gaps auditors find
- Enforcement points cache a prior decision and keep serving access after the underlying authorisation is revoked
- Decision service failure treated as allow, so an outage becomes an authorisation bypass
- Decision inputs not logged, so an assessor cannot tell which policy produced a given grant
Do this for your whole sheet
Paste the rows you run your controls from and get this mapping for every control at once, with the periodic-review ones flagged and a first move per row. No account for the first run.
Build my evidence sheetAC-23 Data Mining Protection. Employ [organization-defined] for [organization-defined] to detect and protect against unauthorized data mining · AC-25 Reference Monitor. Implement a reference monitor for [organization-defined] that is tamperproof, always invoked, and small enough to be subject to analysis and testing, the completeness of which can be assured