SC-23 SC · System and Communications Protection

Session Authenticity

LOW ✓ MODERATE ✓ HIGH
3 Enhancements 1 Overlay 4 Related Controls
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Requirements NIST SOURCE

Protect the authenticity of communications sessions.

Discussion (NIST Supplemental Guidance)

Protecting session authenticity addresses communications protection at the session level, not at the packet level. Such protection establishes grounds for confidence at both ends of communications sessions in the ongoing identities of other parties and the validity of transmitted information. Authenticity protection includes protecting against "man-in-the-middle" attacks, session hijacking, and the insertion of false information into sessions.

Enhancements NIST SOURCE

SC-23(1) Invalidate Session Identifiers at Logout LOW MODERATE HIGH

Invalidate session identifiers upon user logout or other session termination.

Discussion

Invalidating session identifiers at logout curtails the ability of adversaries to capture and continue to employ previously valid session IDs.

Open full page for SC-23(1) →
SC-23(2) User-initiated Logouts and Message Displays WITHDRAWN

Withdrawn. Incorporated into AC-12(1).

SC-23(3) Unique System-generated Session Identifiers LOW MODERATE HIGH

Generate a unique session identifier for each session with [randomness requirements] and recognize only session identifiers that are system-generated.

Discussion

Generating unique session identifiers curtails the ability of adversaries to reuse previously valid session IDs. Employing the concept of randomness in the generation of unique session identifiers protects against brute-force attacks to determine future session identifiers.

Open full page for SC-23(3) →
SC-23(4) Unique Session Identifiers with Randomization WITHDRAWN

Withdrawn. Incorporated into SC-23(3).

SC-23(5) Allowed Certificate Authorities LOW MODERATE HIGH

Only allow the use of [certificated authorities] for verification of the establishment of protected sessions.

Discussion

Reliance on certificate authorities for the establishment of secure sessions includes the use of Transport Layer Security (TLS) certificates. These certificates, after verification by their respective certificate authorities, facilitate the establishment of protected sessions between web clients and web servers.

Open full page for SC-23(5) →

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 SC-23 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. the authenticity of communication sessions is protected.

Examine

[SELECT FROM: System and communications protection policy; procedures addressing session authenticity; system design documentation; system configuration settings and associated documentation; system audit records; system security plan; other relevant documents or records].

Interview

[SELECT FROM: System/network administrators; organizational personnel with information security responsibilities].

Test

[SELECT FROM: Mechanisms supporting and/or implementing session authenticity].

Overlays

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

Not applicable at this tier.

MODERATE

  • Base control: Included (matches standard baseline)

HIGH

  • Base control: Included (matches standard baseline)

STIGs & CCIs

No STIG checks or CCI mappings are currently loaded for SC-23. 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

  • System and communications protection policy
  • system security plan

Configuration

  • system design documentation
  • system configuration settings and associated documentation

Testing

  • Mechanisms supporting and/or implementing session authenticity

Other Records

  • procedures addressing session authenticity
  • system audit records
  • other relevant documents or records