# NIST SP 800-53 Rev. 5 AC-20(5) — Portable Storage Devices -- Prohibited Use

- Source: https://support.icompaas.com/compliance/nist-sp-800-53-rev-5/ac-20-5-portable-storage-devices-prohibited-use
- 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-20(5)`·medium·Component: **Access Control**

## What this control requires

> Prohibits use of organization-controlled portable storage devices on external systems, enforced via technical or process-based methods to prevent data compromise. This control supports the Device Management Policy capability within the Access Control family.
> 
> — NIST SP 800-53 Rev. 5, Control AC-20(5)

### In plain English

Prohibits use of organization-controlled portable storage devices on external systems, enforced via technical or process-based methods to prevent data compromise. 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.

## 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-20(5)) and look for objective evidence on the latest two assessment cycles.

## How to implement

#### 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.
-   **Access.** Document the trigger, the owner and the cadence.
-   **Process.** Document the trigger, the owner and the cadence.
-   **Data.** Document the trigger, the owner and the cadence.
-   **Device.** Document the trigger, the owner and the cadence.
-   **Scope:** management, access control, organization, external systems, capability, storage, policy, devices.

## Evidence to collect

-   **Policy Document.** A signed and version-controlled policy / standard / procedure document.
-   **Infra Scan.** Continuous infrastructure-posture telemetry — AWS Config, Azure Policy compliance, GCP Organisation Policy, Wiz / Prisma findings.

Signed policy or standard documents the safeguard. Focus: Portable Storage Devices -- Prohibited Use.

## Common pitfalls

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

## How it maps to other frameworks

Computed from shared tags, control component and key-operation subjects — handy when you are reconciling controls across an audit.

-   [**NIST SP 800-171 Rev. 3 3.1.20** — Use of External Systems](https://support.icompaas.com/compliance/nist-sp-800-171-rev-3/3-1-20-use-of-external-systems)
-   [**HIPAA (45 CFR Part 164) 164.310(a)(2)(iii)** — Facility Access Controls - Access Control and Validation Procedures](https://support.icompaas.com/compliance/hipaa/164-310-a-2-iii-facility-access-controls-access-control-and-validation-procedures)

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

-   [**Control AC-20(2)** — Portable Storage Devices -- Restricted Use](https://support.icompaas.com/compliance/nist-sp-800-53-rev-5/ac-20-2-portable-storage-devices-restricted-use)
-   [**Control AC-2(3)** — Disable Accounts](https://support.icompaas.com/compliance/nist-sp-800-53-rev-5/ac-2-3-disable-accounts)
-   [**Control AC-20** — Use Of External Systems](https://support.icompaas.com/compliance/nist-sp-800-53-rev-5/ac-20-use-of-external-systems)
-   [**Control AC-2(2)** — Automated Temporary And Emergency Account Management](https://support.icompaas.com/compliance/nist-sp-800-53-rev-5/ac-2-2-automated-temporary-and-emergency-account-management)
-   [**Control AC-2(5)** — Inactivity Logout](https://support.icompaas.com/compliance/nist-sp-800-53-rev-5/ac-2-5-inactivity-logout)
-   [**Control AC-4** — Information Flow Enforcement](https://support.icompaas.com/compliance/nist-sp-800-53-rev-5/ac-4-information-flow-enforcement)

## 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-20(5)`

Topics: governance riskpolicy management

## 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.