NIST SP 800-53 Rev. 5 SC-47 — Alternate Communications Paths

What this control requires

Establish alternate communications paths for system operations and organizational command and control to reduce the risk of a single communication path disruption impacting system operations. This includes designating alternative decision-makers in case primary decision-makers are unavailable and defining their actions during incidents. This control supports the Alternate Communication Systems capability within the System and Communications Protection family.

In plain English

Establish alternate communications paths for system operations and organizational command and control to reduce the risk of a single communication path disruption impacting system operations. In practice, this means you can prove you protection 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.

This control is rated critical in the source catalogue. Treat gaps here as production incidents in the risk register, not housekeeping.

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-47) and look for objective evidence on the latest two assessment cycles.

How to implement

Incident Response

Runbook. Maintain a runbook keyed by incident type with named roles (IC, comms, scribe), an out-of-band comms channel, and a 72-hour timeline for external notification.

Tabletop. Run a quarterly tabletop exercise (ransomware, insider, supply-chain) and feed gaps back into the runbook.

Operational checklist

• Protection. Document the trigger, the owner and the cadence.
• Response. Document the trigger, the owner and the cadence.
• System. Document the trigger, the owner and the cadence.
• Control. Document the trigger, the owner and the cadence.
• Alternate. Document the trigger, the owner and the cadence.
• Scope: management, actions, system, incidents, protection, capability, operations, systems.

Evidence to collect

• Ticketing Workflow. ticketing_workflow evidence

Workflow metrics (ServiceNow, Jira) show approvals and remediation. Focus: Alternate Communications Paths.

Common pitfalls

• Runbooks that name a role but no person, or list a paging channel that no longer exists.

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 3.14.1 — Flaw Remediation
• SOC 2 (2017 TSC) CC7.4 — Incident Response
• ISO/IEC 27001:2022 A.5.27 — Learning from information security incidents

Related controls in NIST SP 800-53 Rev. 5

• Control IR-4(3) — Continuity Of Operations
• Control IR-4(15) — Public Relations And Reputation Repair
• Control IR-4(11) — Integrated Incident Response Team
• Control IR-7(2) — Coordination With External Providers
• Control SC-18(3) — Prevent Downloading And Execution
• Control SI-4(7) — Automated Response To Suspicious Events

References

• NIST Computer Security Resource Center — NIST SP 800-53 Rev. 5
• Catalogue identifier: Control SC-47

Topics: incident responsechange management