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NIST SP 800-171 CUI Protection Center

03.13.08 — Transmission and Storage Confidentiality

Read the official CUI requirement and assessment content, then use the separately labeled Bare Metal Cyber perspective to connect it to implementation, evidence, and sustained operation.

4Source controls
2Assessment objectives
3Assessment methods

03.13 — System and Communications Protection · NIST SP 800-171 Revision 3

Active
Official NIST requirement content

Security requirement

Implement cryptographic mechanisms to prevent the unauthorized disclosure of CUI during transmission and while in storage.

Official NIST discussion

Discussion

This requirement applies to internal and external networks and any system components that can transmit CUI, including servers, notebook computers, desktop computers, mobile devices, printers, copiers, scanners, facsimile machines, and radios. Unprotected communication paths are susceptible to interception and modification. Encryption protects CUI from unauthorized disclosure during transmission and while in storage. Cryptographic mechanisms that protect the confidentiality of CUI during transmission include TLS and IPsec. Information in storage (i.e., information at rest) refers to the state of CUI when it is not in process or in transit and resides on internal or external storage devices, storage area network devices, and databases. Protecting CUI in storage does not focus on the type of storage device or the frequency of access to that device but rather on the state of the information. This requirement relates to 03.13.11.

Bare Metal Cyber interpretation

Implementation perspective

Treat Transmission and Storage Confidentiality as a CUI protection outcome that must be reflected in the system boundary, documented implementation, operational behavior, and assessment evidence. Pay particular attention to secure architecture, boundary protection, communications security, cryptography, and isolation of CUI processing.

  1. Confirm the requirement is in scope for the CUI system components, services, users, and external connections being assessed.
  2. Resolve every organization-defined parameter through an approved governance and tailoring process.
  3. Map each clause of the requirement to an accountable owner, implementation mechanism, and evidence source.
  4. Verify that inherited and shared implementations are supported by current provider evidence and responsibility boundaries.
  5. Collect evidence during normal operation and review changes, exceptions, and deficiencies on a risk-based cadence.

Questions to ask

  • Which CUI assets, data flows, users, and services are protected by this requirement?
  • Which portions are implemented locally, inherited, shared, or not applicable, and what evidence supports that determination?
  • Do the system security plan, deployed configuration, operating process, and assessment evidence tell the same story?
  • What change, incident, or threshold should trigger reassessment?

Evidence and validation

  • network and trust-boundary diagrams
  • firewall and gateway configurations
  • cryptographic configuration and key records
  • segmentation and isolation test results

Common failure patterns

  • diagrams omitting cloud and third-party paths
  • encryption enabled without key governance
  • flat trust zones permitting unnecessary lateral movement
  • boundary rules accumulating without owner review
Official NIST SP 800-171A content

Assessment objectives and methods

Assessment objectives (2)
  1. SR-03.13.8.

    cryptographic mechanisms are implemented to prevent the unauthorized disclosure of CUI during transmission.

  2. SR-03.13.8.

    cryptographic mechanisms are implemented to prevent the unauthorized disclosure of CUI while in storage.

Examine

  • system and communications protection policy and procedures
  • procedures for transmission confidentiality
  • procedures for the protection of information at rest
  • system design documentation
  • system configuration settings
  • cryptographic mechanisms and associated configuration documentation
  • information in storage requiring confidentiality protection
  • system audit records
  • system security plan
  • other relevant documents or records

Interview

  • personnel with information security responsibilities
  • system developers
  • system administrators

Test

  • mechanisms for supporting or implementing transmission confidentiality
  • cryptographic mechanisms for supporting or implementing transmission confidentiality
  • mechanisms for supporting or implementing confidentiality protection for information in storage
  • cryptographic mechanisms for implementing confidentiality protections for information in storage
Official source-control relationships

Source NIST SP 800-53 controls

These controls are referenced by the official SP 800-171 Rev. 3 OSCAL record. Open the corresponding control pages for complete control text, enhancements, D3FEND mappings, and related learning.

Source controlSC-8Open SP 800-53 control →Source controlSC-8(1)Open SP 800-53 control →Source controlSC-28Open SP 800-53 control →Source controlSC-28(1)Open SP 800-53 control →
Source record

Authoritative sources

Bare Metal Cyber is an independent educational publisher and is not affiliated with or endorsed by NIST. The official publications, the responsible federal agency, and the governing contract or agreement determine applicability, tailoring, assessment depth, and required implementation.