Control statement
- a.Use internal system clocks to generate time stamps for audit records; and
- b.Record time stamps for audit records that meet [Organization-defined: granularity of time measurement] and that use Coordinated Universal Time, have a fixed local time offset from Coordinated Universal Time, or that include the local time offset as part of the time stamp.
Discussion
Time stamps generated by the system include date and time. Time is commonly expressed in Coordinated Universal Time (UTC), a modern continuation of Greenwich Mean Time (GMT), or local time with an offset from UTC. Granularity of time measurements refers to the degree of synchronization between system clocks and reference clocks (e.g., clocks synchronizing within hundreds of milliseconds or tens of milliseconds). Organizations may define different time granularities for different system components. Time service can be critical to other security capabilities such as access control and identification and authentication, depending on the nature of the mechanisms used to support those capabilities.
Organization-defined parameters
These values must be resolved through the organization’s tailoring and governance process. Bracketed parameter references in the control text identify where a decision is required.
From control text to operational evidence
Use Time Stamps as a testable risk decision. Translate the official statement into accountable people, repeatable processes, configured technology, and evidence that demonstrates the outcome over time. In this family, pay particular attention to audit event design, trustworthy collection, retention, review, and investigation support.
Implementation workflow
- Define the control boundary, responsible owner, inherited portions, and systems or processes in scope.
- Resolve each organization-defined parameter before declaring the control implemented.
- Document how the implementation satisfies every clause of the official control statement.
- Collect evidence as a normal byproduct of operation rather than only before an assessment.
- Review exceptions, changes, and monitoring results on a risk-based cadence.
Evidence examples
- logging standards and event-selection decisions
- sample audit records and retention settings
- time-synchronization evidence
- alert and review records
Common failure patterns
- collecting logs without defined use cases
- critical events missing from the audit trail
- retention shorter than investigative needs
- logs accessible to the same administrators being monitored
Questions practitioners should ask
- What risk decision is this control intended to support in this system?
- Which parts are implemented locally, inherited, shared, or not applicable—and what evidence supports that decision?
- Do the documented narrative, deployed configuration, operating process, and collected evidence agree?
- What event or threshold requires the implementation to be reviewed or changed?
Assessment objectives and methods
Show the assessment objective
- AU-08a.internal system clocks are used to generate timestamps for audit records;
- AU-08b.timestamps are recorded for audit records that meet [Organization-defined: granularity of time measurement] and that use Coordinated Universal Time, have a fixed local time offset from Coordinated Universal Time, or include the local time offset as part of the timestamp.
Examine
- Audit and accountability policy
- system security plan
- privacy plan
- procedures addressing timestamp generation
- system design documentation
- system configuration settings and associated documentation
- system audit records
- other relevant documents or records
Interview
- Organizational personnel with information security and privacy responsibilities
- system/network administrators
- system developers
Test
- Mechanisms implementing timestamp generation
Related controls
These relationships come from the official OSCAL catalog. They indicate useful dependencies or context, not automatic inheritance or equivalence.
Control enhancements
Enhancements add specificity, strength, or scope to the base control. Baseline badges show explicit selections in the official SP 800-53B OSCAL profiles.
AU-8(1) — Synchronization with Authoritative Time Source
This enhancement is marked withdrawn in the official OSCAL catalog. Related-control metadata below may identify where its intent was incorporated.
AU-8(2) — Secondary Authoritative Time Source
This enhancement is marked withdrawn in the official OSCAL catalog. Related-control metadata below may identify where its intent was incorporated.
Authoritative sources
Bare Metal Cyber is an independent educational publisher and is not affiliated with or endorsed by NIST. Official control requirements and interpretations remain with NIST and the responsible authorizing organization.