What evidence do auditors commonly ask for on AC-3(15) Access Enforcement | Discretionary and Mandatory Access Control?

Access control policy; Procedures addressing access enforcement; System design documentation; System configuration settings and associated documentation; List of subjects and objects (i.e., users and resources) requiring enforcement of mandatory access control policies; List of subjects and objects (i.e., users and resources) requiring enforcement of discretionary access control policies.

What is the most common gap auditors find on AC-3(15)?

Only one of the mandatory and discretionary access control policies is enforced over the covered subjects and objects

NIST SP 800-53 Rev 5 · AC - Access Control

`AC-3(15)` Access Enforcement | Discretionary and Mandatory Access Control

(a) Enforce organization-defined mandatory access control policy over the set of covered subjects and objects specified in the policy; and (b) Enforce organization-defined discretionary access control policy over the set of covered subjects and objects specified in the policy.

Source: NIST SP 800-53 Rev 5, AC-3(15). The statement above is our statement of the clause, read from the published text and cited so you can check it against the official text, not the instrument verbatim. Open NIST SP 800-53 Rev 5 in the compliance library.

Base controls and their enhancements. Which apply follows the baseline you are assessed against (for example FedRAMP Moderate or High, or the low, moderate and high baselines of SP 800-53B). Text in square brackets is a parameter your organisation sets.

artefacts

held by a system

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. To go live: easy when half or more of the artefacts are already held by a system, moderate from a quarter to a half, hard below a quarter.

These are the artefacts auditors commonly ask for on this requirement, our guidance rather than text from the standard. Your assessor decides what is sufficient in your context, and asks for samples across the period when a report covers one.

system holds itEvidence a system already holds

List of subjects and objects (i.e., users and resources) requiring enforcement of mandatory access control policies · Identity provider / directory
List of subjects and objects (i.e., users and resources) requiring enforcement of discretionary access control policies · Identity provider / directory

periodic reviewEvidence produced at each review

System audit records · Identity provider / directory
Test of Mechanisms implementing mandatory and discretionary access control policy · Identity provider / directory

governing documentDocuments that govern the control

Access control policy · Policy repository / GRC workspace
Procedures addressing access enforcement · Policy repository / GRC workspace
System design documentation · Policy repository / GRC workspace
System configuration settings and associated documentation · Policy repository / GRC workspace
System security plan · Policy repository / GRC workspace

First move

Mostly documents and reviews. Pull the 2 system-held artefacts from your Identity provider / directory on a schedule; put the documents under version control with an owner and review date, and log each review as a dated record with a named reviewer.

Common gaps auditors find

Only one of the mandatory and discretionary access control policies is enforced over the covered subjects and objects
Mandatory and discretionary policies conflict because their covered subjects and objects were never reconciled

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 sheet

AC-3(14) Access Enforcement | Individual Access · AC-4 Information Flow Enforcement