NIST SP 800-53 Rev. 5 SC-7(23) — Disable Sender Feedback On Protocol Validation Failure

What this control requires

Disable feedback to senders when there is a failure in protocol validation format. This prevents adversaries from gaining valuable information that could aid them in exploiting protocol vulnerabilities. This control supports the Protocol Validation System capability within the System and Communications Protection family.

In plain English

Disable feedback to senders when there is a failure in protocol validation format. 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 System and Communications Protection, the assessor will trace your implementation back to the catalogue reference (Control SC-7(23)) 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.

Vulnerability Management

Scanners. Pair an unauthenticated scanner (Nessus / Qualys / Tenable.io) for external surface with an authenticated agent for OS/library CVEs on every host.

SLA. Document remediation SLAs by CVSS / EPSS: critical 7 days, high 30 days, medium 90 days; report monthly trend to leadership.

Containers. Scan images in CI (Trivy / Grype / Snyk Container) AND at runtime; block deploys on critical findings without exception.

Operational checklist

• Policy. Document the trigger, the owner and the cadence.
• Disable. Document the trigger, the owner and the cadence.
• Information. Document the trigger, the owner and the cadence.
• Validation. Document the trigger, the owner and the cadence.
• Protection. Document the trigger, the owner and the cadence.
• Scope: management, information, system, feedback, failure, protection, capability, policy.

Evidence to collect

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

Signed policy or standard documents the safeguard. Focus: Disable Sender Feedback On Protocol Validation Failure.

Common pitfalls

• Policies that no engineer has read; the version in Confluence drifts from the version that's actually being enforced.
• Scans that hit only the perimeter; missing authenticated scans of OS, runtime libs and base images so most CVEs are invisible.

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.

• ISO/IEC 27001:2022 A.8.8 — Management of technical vulnerabilities
• NIST SP 800-171 Rev. 3 3.14.3 — Security Alerts, Advisories, and Directives
• CIS Controls v8 7.1 — Establish and Maintain a Vulnerability Management Process
• BSI C5:2020 OIS-05 — Contact with Relevant Government Agencies and Interest Groups
• HIPAA (45 CFR Part 164) 164.308(a)(1)(ii)(D) — Security Management Process -Information System Activity Review

Related controls in NIST SP 800-53 Rev. 5

• Control SC-5(2) — Capacity, Bandwidth, And Redundancy
• Control SC-15(4) — Explicitly Indicate Current Participants
• Control SC-8(2) — Pre- And Post-Transmission Handling
• Control SC-12(2) — Symmetric Keys
• Control SC-8(4) — Conceal Or Randomize Communications
• Control SC-16(1) — Integrity Verification

References

• NIST Computer Security Resource Center — NIST SP 800-53 Rev. 5
• Catalogue identifier: Control SC-7(23)

Topics: governance riskpolicy managementvulnerability management