# NIST SP 800-53 Rev. 5 AC-4(3) — Dynamic Information Flow Control

- Source: https://support.icompaas.com/compliance/nist-sp-800-53-rev-5/ac-4-3-dynamic-information-flow-control
- Section: [Compliance](https://support.icompaas.com/compliance) › [NIST SP 800-53 Rev. 5 Controls](https://support.icompaas.com/compliance/nist-sp-800-53-rev-5) › AC — Access Control
- Last updated: 2026-06-05
- Publisher: iCompaas, Inc. (https://www.icompaas.com)

**NIST SP 800-53 Rev. 5**·Control `AC-4(3)`·high·Component: **Access Control**

## What this control requires

> Organizations must enforce defined information flow control policies that adapt to changing conditions or operational needs. Dynamic information flow control allows or disallows information flows based on factors such as changes in risk tolerance, mission or business needs, the threat environment, and the detection of potentially harmful events. This control supports the Governance capability within the Access Control family.
> 
> — NIST SP 800-53 Rev. 5, Control AC-4(3)

### In plain English

Organizations must enforce defined information flow control policies that adapt to changing conditions or operational needs. In practice, this means you can prove you policy management-level controls on a defined cadence.

## Why it matters

SP 800-53 is the catalogue every U.S. federal authorisation (FedRAMP, FISMA, CMMC) and most regulated industries point at. A missing control surfaces as a Plan of Action & Milestones (POA&M) item that an Authorizing Official must approve before the Authority To Operate is granted or renewed.

This control is rated **high**. Auditors expect a named owner, a remediation SLA, and a tooling artefact that evidences continuous operation.

## What an auditor looks for

A 3PAO (FedRAMP) or Independent Assessor (NIST RMF) tests against NIST SP 800-53A assessment procedures. For each control they expect a documented implementation that addresses every assessment objective (Examine, Interview, Test) and an implementation summary in the System Security Plan.

Within **Access Control**, the assessor will trace your implementation back to the catalogue reference (Control AC-4(3)) and look for objective evidence on the latest two assessment cycles.

## How to implement

#### Code Review Testing

**Pipeline.** Require at least one human reviewer plus passing CI (lint, type, unit, security scan) before merge — protected branches enforce this.

#### Policy Management

**Docs.** Keep each policy in version-controlled Markdown alongside the code that implements it; ship a signed PDF snapshot at each annual review and link the SHA into the SoA.

### Operational checklist

-   **Policy.** Document the trigger, the owner and the cadence.
-   **Dynamic.** Document the trigger, the owner and the cadence.
-   **Access.** Document the trigger, the owner and the cadence.
-   **Information.** Document the trigger, the owner and the cadence.
-   **Flow Control.** Document the trigger, the owner and the cadence.
-   **Scope:** management, conditions, access control, information, information flow control, mission, business needs, threat environment.

## Evidence to collect

-   **Policy Document.** A signed and version-controlled policy / standard / procedure document.

Signed policy or standard documents the safeguard. Focus: Dynamic Information Flow Control.

## Common pitfalls

-   Policies that no engineer has read; the version in Confluence drifts from the version that's actually being enforced.

## Related controls in NIST SP 800-53 Rev. 5

-   [**Control AC-4(2)** — Processing Domains](https://support.icompaas.com/compliance/nist-sp-800-53-rev-5/ac-4-2-processing-domains)
-   [**Control AC-4(4)** — Flow Control Of Encrypted Information](https://support.icompaas.com/compliance/nist-sp-800-53-rev-5/ac-4-4-flow-control-of-encrypted-information)
-   [**Control AC-4** — Information Flow Enforcement](https://support.icompaas.com/compliance/nist-sp-800-53-rev-5/ac-4-information-flow-enforcement)
-   [**Control AC-4(6)** — Metadata](https://support.icompaas.com/compliance/nist-sp-800-53-rev-5/ac-4-6-metadata)
-   [**Control PM-16(1)** — Automated Means For Sharing Threat Intelligence](https://support.icompaas.com/compliance/nist-sp-800-53-rev-5/pm-16-1-automated-means-for-sharing-threat-intelligence)
-   [**Control AC-3(15)** — Discretionary And Mandatory Access Control](https://support.icompaas.com/compliance/nist-sp-800-53-rev-5/ac-3-15-discretionary-and-mandatory-access-control)

## References

-   [NIST Computer Security Resource Center — NIST SP 800-53 Rev. 5](https://csrc.nist.gov/Projects/risk-management/sp800-53-controls)
-   Catalogue identifier: `Control AC-4(3)`

Topics: governance riskcode review testingpolicy managementthreat intelligence

## Related compliance guidance

- [NIST SP 800-53 Rev. 5: a practical implementation guide for cloud teams](https://support.icompaas.com/compliance/nist-sp-800-53-rev-5): Start with the full NIST SP 800-53 implementation guide — scope, roadmap, evidence and how the assessment runs.
- [NIST SP 800-171 and CMMC: a practical guide to protecting CUI in the cloud](https://support.icompaas.com/compliance/nist-sp-800-171-rev-3): If your obligation is protecting CUI in your own systems for a federal or defence contract, this derived subset — not the full catalogue — is the requirement.
- [SOC 2 compliance: a practical implementation guide for cloud-native SaaS teams](https://support.icompaas.com/compliance/soc-2-trust-services-criteria): Most commercial SaaS already hold a SOC 2 Type 2, and FedRAMP 20x Class A is designed for providers that have one.