NIST SP 800-53 Rev. 5 SI-22 — Information Diversity

What this control requires

Identify alternative information sources for essential functions and services, and use these sources when the primary information source is unavailable or corrupted. This ensures continuity of critical functions even when primary sources are compromised, though the alternative sources may provide less precise or accurate data. This control supports the System Resilience, Disaster Recovery capability within the System and Information Integrity family.

In plain English

Identify alternative information sources for essential functions and services, and use these sources when the primary information source is unavailable or corrupted. In practice, this means you can prove you information information-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 high. Auditors expect a named owner, a remediation SLA, and a tooling artefact that evidences continuous operation.

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 Information Integrity, the assessor will trace your implementation back to the catalogue reference (Control SI-22) and look for objective evidence on the latest two assessment cycles.

How to implement

Secure Development

Pipeline. Require code review, SAST (Semgrep / Snyk Code), SCA (Dependabot / Renovate), secret-scanning and IaC scanning in the merge pipeline.

Branch protection. Protected branches enforce reviews, signed commits and passing CI before merge; document the protection rules as the control evidence.

Code Review Testing

Pipeline. Require at least one human reviewer plus passing CI (lint, type, unit, security scan) before merge — protected branches enforce this.

Business Continuity

BC/DR. Define RTO/RPO per service, test backup restoration quarterly, and run a tabletop of full-region failover annually.

Backups. Immutable backups (S3 Object Lock / Azure immutable storage / GCS bucket lock) plus an air-gapped copy for ransomware resilience.

Operational checklist

• Information. Document the trigger, the owner and the cadence.
• Data. Document the trigger, the owner and the cadence.
• Review. 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.
• Scope: information, system, functions, source, sources, review, services, recovery.

Evidence to collect

• Code Repo Scan. Source-control evidence — branch protection, required reviewers, CI status, SCA / SAST reports.

Source control pipelines (GitHub, GitLab) enforce SDLC guardrails. Focus: Information Diversity.

Common pitfalls

• CI security checks set to warn-only; the merge button is faster than the security feedback.
• DR plans that have never been tested in earnest, or that depend on an MFA token only one person can produce.

Related controls in NIST SP 800-53 Rev. 5

• Control SA-12(13) — Critical Information System Components
• Control CP-10 — System Recovery And Reconstitution
• Control SI-8(3) — Continuous Learning Capability
• Control SI-10(6) — Injection Prevention
• Control SI-19(6) — Differential Privacy
• Control SI-7(6) — Cryptographic Protection

References

• NIST Computer Security Resource Center — NIST SP 800-53 Rev. 5
• Catalogue identifier: Control SI-22

Topics: business continuitysecure developmentcode review testingdevsecops