Synchronization with Authoritative Time Source
High Risk
Moderate
Low Cost
AU-8(1) — Synchronization with Authoritative Time Source. Synchronize time with authoritative source — moved to SC-45(1). Keep NTP/chrony sync for audit timestamps on ePHI systems. Note: NIST SP 800-53 Rev. 5 status — Moved to SC-45(1).
Control Objective
Operationalize AU-8(1) (Synchronization with Authoritative Time Source) so ePHI systems meet NIST intent with measurable healthcare safeguards and audit-ready evidence.
Implementation Guidance
- Confirm applicability of AU-8(1) in your baseline/SSP; if withdrawn, map to the incorporation target and keep residual evidence.\n2. Scope the control to systems and workflows that create, receive, maintain, or transmit ePHI (plus critical supporting infrastructure).\n3. Implement technical and procedural safeguards described for this enhancement; prefer centralized IdP/SIEM/IR tooling where possible.\n4. Define owners, SLAs, and monitoring/alerting so failures are visible.\n5. Document configuration baselines and integrate with change control.\n6. Train affected workforce (clinical, IT, privacy) on new behaviors and break-glass paths.\n7. Test with tabletop or technical validation; retain artifacts.\n8. Review annually and after major EHR/IdP/IR tooling changes.
Real-World Use Cases
How this control shows up in healthcare and HIPAA-covered environments.
Best Practices
- Treat Synchronization with Authoritative Time Source as a measurable control, not a policy slogan.\n- Prioritize systems with ePHI and privileged paths first.\n- Preserve audit evidence and ticket linkage.\n- Coordinate security, privacy, and clinical operations.\n- Document withdrawn/inherited mappings clearly for assessors.\n- Re-test after EHR and identity platform upgrades.
Common Gaps & Violations
- Title still reads as a placeholder ('Enhanced …') with empty use cases.\n- Control marked inherited/withdrawn with no mapping to the live control.\n- Implementation exists on paper only — no configs, logs, or tickets.\n- Clinical systems excluded without risk analysis.\n- No owner or review cadence.
Required Documentation
- AU-8(1) implementation standard / procedure\n- System security plan control narrative\n- Configuration evidence and diagrams\n- Training or awareness records where applicable\n- Test/tabletop or monitoring samples
How to Test & Validate
- Verify AU-8(1) narrative matches actual configuration for a sample ePHI system.\n2. Trace one recent event (auth, audit, or incident) that exercises the enhancement.\n3. Confirm monitoring/alerting or review evidence exists.\n4. Check withdrawn controls map to the incorporation target.\n5. Interview owners for break-glass and failure handling.
Audit Considerations
Assessors look for real operational proof of Synchronization with Authoritative Time Source on systems with ePHI — configs, logs, tickets, and trained owners — not only a copied NIST statement.
HIPAA Mapping
How this NIST control supports HIPAA Security Rule expectations.
- 164.312(b) Audit Controls — mechanisms that record and examine activity in systems containing ePHI.\n- 164.308(a)(1)(ii)(D) Information System Activity Review — regular review of audit logs, access reports, and security incidents.\n- 164.316(b) Documentation — retain required documentation for six years; audit evidence often supports investigations longer by policy.\n- 164.308(a)(6) Security Incident Procedures — audit data fuels detection and response.
Compliance Tips
- Map AU-8(1) explicitly in the SSP to HIPAA safeguards; keep evidence packets ready for assessors.
References & Resources
- NIST SP 800-53 Rev. 5 — AU-8(1)\n- HIPAA Security & Breach Notification Rules\n- Related: SC-45(1), AU-8, AU-12(1)
Related Guidelines
Related controls that commonly accompany AU-8(1).
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