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AC-20(4) AC · Access Control

Network Accessible Storage Devices — Prohibited Use

LOW MODERATE HIGH
1 Overlay 0 Related Controls
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Requirements NIST SOURCE

Prohibit the use of [network-accessible storage devices] in external systems.

Discussion (NIST Supplemental Guidance)

Network-accessible storage devices in external systems include online storage devices in public, hybrid, or community cloud-based systems.

Implementation Guidance

Engineering Interpretation

Original engineering commentary written for this explorer — not NIST source text and not authoritative guidance.

No engineering interpretation has been authored for AC-20(4) yet. This section is architected to receive it — see the Requirements and Assessment sections above for the authoritative NIST source content in the meantime.

Assessment

NIST SP 800-53A REV 5.2.0

Assessment Objectives

  1. network-accessible storage devices prohibited from use in external systems are defined;
  2. the use of <AC-20(04)_ODP network-accessible storage devices> is prohibited in external systems.

Examine

[SELECT FROM: Access control policy; procedures addressing use of network-accessible storage devices in external systems; system design documentation; system configuration settings and associated documentation; system connection or processing agreements; list of network-accessible storage devices prohibited from use in external systems; system audit records; system security plan; other relevant documents or records].

Interview

[SELECT FROM: Organizational personnel with responsibilities for prohibiting the use of network-accessible storage devices in external systems; system/network administrators; organizational personnel with information security responsibilities].

Test

[SELECT FROM: Mechanisms prohibiting the use of network-accessible storage devices in external systems].

Overlays

Showing the OT/ICS overlay for the parent control AC-20 — see the AC-20(4) entries within each baseline below.

OT/ICS Overlay SP 800-82r3

NIST SP 800-82r3 Appendix F, Table 22. Blank baseline means the control/control enhancement is not selected in that initial OT baseline.

LOW

  • Base control: Included (matches standard baseline)

MODERATE

  • Base control: Included (matches standard baseline)
  • Included: (1) (2)

HIGH

  • Base control: Included (matches standard baseline)
  • Included: (1) (2)

STIGs & CCIs

No STIG checks or CCI mappings are currently loaded for AC-20(4). This section is architected to display, per product: STIG ID, Finding ID, Severity, Title, Description, Check, Fix, CCI, and NIST control mapping — but nothing is populated here until a real DISA STIG/CCI dataset is ingested.

Learn more about STIG/CCI integration →

Evidence

Potential Evidence — Derived

Categorized from the SP 800-53A "Examine"/"Test" artifact list above by keyword — not an authoritative NIST evidence list.

Policy

  • Access control policy
  • system security plan

Configuration

  • system design documentation
  • system configuration settings and associated documentation

Testing

  • Mechanisms prohibiting the use of network-accessible storage devices in external systems

Other Records

  • procedures addressing use of network-accessible storage devices in external systems
  • system connection or processing agreements
  • list of network-accessible storage devices prohibited from use in external systems
  • system audit records
  • other relevant documents or records