03.01.02: Access Enforcement

To meet the 03.01.02: access enforcement requirement, you must technically enforce approved access rules for every system that stores, processes, or transmits CUI, and prove those rules work in day-to-day operations. Translate policy into system controls (RBAC/ABAC, ACLs, network segmentation, app authorization), assign owners, and retain evidence that enforcement is continuous and tested. ¹

Key takeaways:

• Access decisions must be enforced by systems, not left to user behavior or policy text. ¹
• Scope matters: enforcement must cover the full CUI environment, including identity, endpoints, apps, and networks. ¹
• Audits are won with artifacts: SSP mapping, configs, logs, reviews, and test results tied to owners and components. ¹

03.01.02 is where “we have access rules” stops being a policy statement and becomes an engineering requirement. Examiners and assessors expect you to show that access is constrained by design across the CUI boundary: users, administrators, services, devices, and third-party connections only get the access that has been authorized, and the environment enforces that authorization in real time. ¹

Operationally, this requirement forces tight alignment between identity governance (who gets access), technical control points (how the system enforces it), and evidence (how you prove it kept working). Many programs fail here because they document role descriptions but cannot show where those roles are implemented, or they rely on manual procedures that are routinely bypassed (shared accounts, local admin, exceptions that never expire, flat networks).

This page gives you requirement-level guidance you can execute quickly: how to define enforcement points, how to implement and test them, what artifacts to retain, and what assessors commonly challenge. It is written for a Compliance Officer, CCO, or GRC lead coordinating IT, security engineering, and system owners supporting CUI workloads. ¹

Regulatory text

Requirement: “NIST SP 800-171 Rev. 3 requirement 03.01.02 (Access Enforcement).” ¹

Operator translation (what you must do):

• Define the access rules that apply to CUI systems (who/what can access which resources, under what conditions).
• Implement technical mechanisms that enforce those rules at the relevant control points (identity provider, OS, application, database, network, cloud control plane).
• Demonstrate the mechanisms operate as intended and remain effective over time through repeatable evidence. ¹

Because the provided excerpt is short, your job is to operationalize “enforcement” in a way an assessor can validate: a clear scope boundary, named systems, configured controls, and proof that unauthorized access is blocked.

Plain-English interpretation (what “access enforcement” means)

Access enforcement means the system makes access decisions and blocks disallowed actions. A written policy is not enforcement. A role chart is not enforcement. Enforcement is what happens when:

• A user without the right role tries to open a CUI folder and gets denied.
• A service account tries to query a database table outside its authorization and fails.
• A third party support session can only reach approved admin interfaces, not the whole network.

You should assume assessors will test negative cases (attempt access that should be denied) and will ask where the decision is made (app layer, OS ACL, database permissions, network firewall, cloud IAM). If you cannot point to the control point, you do not have enforceable access control. ¹

Who it applies to (entity and operational context)

Applies to nonfederal organizations handling CUI, including defense contractors and federal contractors, for any system component that stores, processes, or transmits CUI. ¹

In practice, expect to include:

• Identity systems (IdP, directory services, SSO, MFA stack)
• Endpoints used to access CUI (managed workstations, VDI)
• Collaboration and storage (file shares, SharePoint-like platforms, object storage buckets)
• Line-of-business apps that process CUI (web apps, ERP modules, ticketing, engineering tools)
• Databases and data platforms
• Network and remote access paths (VPN/ZTNA, bastions, jump boxes)
• Cloud control planes (IAM, security groups, KMS permissions)
• Third-party access methods (support tools, MSP admin portals, supplier connectivity)

If you have multiple enclaves, enforcement must be demonstrable per enclave, with clear boundaries and inherited controls documented in your SSP. ¹

What you actually need to do (step-by-step)

1) Define the enforcement scope and boundary (CUI system inventory)

• Identify which systems are in-scope for CUI and document the boundary (network segments, tenant/subscription, applications, repositories).
• List the “decision points” where access is granted or denied (IdP conditional access, app authorization checks, file ACLs, database roles, firewall rules).
• Assign an accountable owner for each decision point (system owner or control owner). ¹

Deliverable: SSP statements that map 03.01.02 to specific components and owners. ¹

2) Specify access rules in a way engineers can implement

Define access rules as testable requirements, for example:

• Role-based rules (RBAC): “Engineering role can read Project A CUI repository; cannot write to release folder.”
• Attribute-based rules (ABAC): “Only managed devices with compliant posture can access CUI apps.”
• Administrative separation: “Only IT admins in privileged group can access management plane; no standard user has local admin on CUI endpoints.”

Keep rules tied to business need and data sensitivity. Avoid “everyone in department” access unless you can justify it and show it is enforced. ¹

3) Implement technical enforcement at each control point

Common enforcement mechanisms you should expect to configure and evidence:

• Identity enforcement: group membership, conditional access, session controls, service account restrictions.
• Endpoint enforcement: removal of local admin, application allowlisting where appropriate, device posture gates for CUI access.
• Application enforcement: authorization middleware, least-privilege service roles, protected admin routes.
• Data enforcement: file/folder ACLs, database roles, row/table permissions where needed, bucket policies.
• Network enforcement: segmentation, firewall allowlists, remote admin via bastion, restrict east-west traffic for CUI segments.
• Cloud enforcement: IAM policies, resource policies, security groups, permission boundaries.

Document “what enforces what.” If you cannot explain it in one sentence per control point, your SSP is not audit-ready. ¹

4) Validate enforcement with negative testing (prove denials)

Build a small test suite that produces evidence:

• Attempt access as a user without privileges (should fail).
• Attempt privileged action as standard user (should fail).
• Attempt access from an unmanaged device (should fail, if that is your rule).
• Attempt network connection from non-CUI segment into CUI assets (should fail).

Capture screenshots, logs, and test scripts. Tie each test to a requirement statement in the SSP. ¹

5) Operationalize: change control, exceptions, and periodic review

• Put access rule changes under change management (ticket, approval, implementation record).
• Define an exception process with documented business justification, compensating controls, and an expiry date.
• Run periodic access reviews for high-risk groups (privileged admin, CUI repository owners, service accounts) and retain evidence of review and remediation. ¹

6) Close gaps with POA&M discipline

If enforcement is incomplete (legacy app cannot enforce granular authorization, flat network, unclear ownership), track it:

• record the gap
• assign owner
• set target completion date
• validate closure with test evidence before marking complete ¹

Daydream can help here by keeping 03.01.02 mapped to SSP language, owners, and recurring evidence requests, so you are not rebuilding audit packages each cycle. ¹

Required evidence and artifacts to retain

Keep artifacts tied to (a) scope, (b) configuration, and (c) proof of operation:

Core documentation

• System Security Plan (SSP) section for 03.01.02 with: boundary, enforcement points, control owners, and implementation statements. ¹
• Access control policy/standard that defines roles, least privilege approach, exception handling, and review expectations. ¹
• Network/data flow diagrams for CUI boundary showing segmentation and access paths. ¹

Technical configuration evidence (examples)

• IAM policy exports, group and role definitions, conditional access rules
• Firewall rules, security group exports, NAC/ZTNA policies
• Application authorization configuration (admin role mappings, permission matrices)
• File share ACL exports, repository permissions reports
• Database role grants / permission scripts

Operating evidence

• Access request and approval tickets (including privileged access)
• Periodic access review reports and remediation tickets
• Logs showing denied access attempts and admin activity (where available)
• Test results for negative access attempts (screenshots, scripts, SIEM queries)
• POA&M entries for any incomplete enforcement and closure validation ¹

Common exam/audit questions and hangups

Assessors tend to probe these points:

• “Show me, in the system, where access is enforced for CUI repositories.” ¹
• “Which systems are in-scope, and how do you know?” (boundary clarity) ¹
• “How do you prevent privilege creep in admin groups?” ¹
• “Do service accounts have only the permissions they need, and can you prove it?” ¹
• “How do you control third-party remote access into the CUI environment?” ¹

Hangups that slow audits:

• SSP describes intentions, not configurations.
• Teams provide a policy PDF but no system exports or test evidence.
• Multiple sources of truth for identity (local accounts, app accounts, directory accounts) with inconsistent enforcement. ¹

Frequent implementation mistakes (and how to avoid them)

1. Documenting roles without implementing them.
   Fix: build a permission matrix that maps each role to each system component and show where it is configured (group, policy, ACL). ¹

2. Flat networks with “trusted internal” assumptions.
   Fix: segment the CUI environment and restrict admin paths through controlled gateways. Document the segmentation rule set and keep exports. ¹

3. Local accounts and shared admin credentials.
   Fix: centralize identity, disable shared accounts, require named admin roles, and keep an exception register for anything that cannot be migrated yet. ¹

4. Service accounts with broad permissions that never expire.
   Fix: inventory service principals, justify permissions, and schedule periodic review with evidence of recertification. ¹

5. No negative testing.
   Fix: run and record “should be denied” tests after major changes and on a cadence that matches your change volume. ¹

Enforcement context and risk implications

No public enforcement cases were provided in the source catalog for this requirement, so this page does not cite specific cases.

Risk-wise, weak access enforcement is a common root cause of CUI exposure because it allows lateral movement, overbroad sharing, and unauthorized administrative access. For compliance, the typical failure mode is evidence: you may have controls configured, but cannot produce exports, logs, or test results tied back to 03.01.02 and your SSP. ¹

Practical 30/60/90-day execution plan

First 30 days (stabilize and define)

• Confirm CUI boundary and inventory in-scope systems; name the enforcement points per system. ¹
• Update SSP language for 03.01.02: components, owners, and how enforcement is implemented. ¹
• Identify the highest-risk access paths (admin access, remote access, external sharing) and document current state configs.

Days 31–60 (implement and test)

• Close obvious enforcement gaps: remove shared accounts, lock down privileged groups, restrict third-party access paths, tighten repository permissions.
• Create a permission matrix for CUI data stores and key apps; align roles/groups to the matrix.
• Run negative tests for top systems and store evidence (denials, logs, screenshots). ¹

Days 61–90 (operate and prove)

• Stand up recurring access reviews for privileged roles, CUI repositories, and service accounts; track remediation to completion. ¹
• Formalize exception handling with expirations and compensating controls; reflect exceptions in POA&M. ¹
• Build an audit-ready evidence pack per system: SSP mapping, config exports, review records, and test results.

If you manage this in Daydream, structure the workspace around “system component → enforcement point → evidence,” then attach recurring tasks and evidence requests to the control owner so collection does not depend on last-minute scrambles. ¹

Frequently Asked Questions

Does 03.01.02 require role-based access control (RBAC) specifically?

The text provided states “Access Enforcement,” not a specific model. Use RBAC, ABAC, ACLs, or a combination, as long as the system enforces approved access rules and you can prove it with configuration and test evidence. ¹

What’s the fastest way to show “enforcement” to an assessor?

Pick two or three high-impact systems (IdP, primary CUI repository, key CUI application) and produce: policy-to-config mapping, exported permissions, and a short negative test that demonstrates access denial. Tie each artifact to the SSP statement for 03.01.02. ¹

Are logs required for access enforcement?

The excerpt does not explicitly say “logging,” but logs are often the most practical operating evidence that controls are working over time. Keep what you have (denied events, admin actions) and pair it with periodic review records and test results. ¹

How do I handle legacy applications that can’t enforce granular permissions?

Treat it as a scoped risk: restrict access upstream (network segmentation, jump hosts, tightly controlled groups), document compensating controls in the SSP, and track remediation in the POA&M until the app is replaced or redesigned. ¹

Does this apply to third-party access (MSP, supplier support, SaaS admins)?

Yes if the third party can reach systems that store, process, or transmit CUI. Enforce access through controlled identities, limited network paths, and time-bound approvals, and retain evidence of those restrictions and reviews. ¹

What evidence do I need if access is enforced by a cloud provider’s native IAM?

Keep exported IAM policies/roles, resource policies, group membership, and configuration screenshots or change records that show the rules in effect. Add a simple negative test result showing a denied action for a non-authorized identity. ¹

Footnotes

1. NIST SP 800-171 Rev. 3