Mapped Requirement and Assessment Objective
Mapped to NIST 800-171 requirement 3.3.4 and CMMC assessment objective AU.L2-3.3.4[a].
What This Objective Means
To support consistent, reliable audit logging, organizations must identify which systems generate timestamps for key events such as user logins, file access, system alerts, and administrative actions.
This objective also supports later time-synchronization expectations by clarifying where timestamps originate across the environment and whether systems timestamp events locally or depend on another source.
Why Timestamp Sources Matter
Timestamps enable investigators and defenders to detect unauthorized activity, correlate events across systems, and reconstruct incident timelines during or after an event.
If timestamp sources are unknown or inconsistent, audit records may not be dependable for monitoring, investigation, or assessment evidence.
How to Implement AU 3.3.4a
Start by reviewing your system inventory to identify devices and services that generate audit logs, such as servers, workstations, network devices, firewalls, and cloud services. Determine which components produce timestamps natively and which rely on another system.
Document these time-stamping responsibilities in your System Security Plan (SSP) and related artifacts used to demonstrate NIST 800-171 compliance. Include whether each system uses an internal time source or synchronizes to an external source (for example, NTP).
Evidence Assessors Commonly Expect
Maintain a documented list of systems that produce time-stamped audit logs, along with inventory records or network diagrams showing where logs originate and which systems apply timestamps.
Include time configuration details (such as synchronization settings and approved time sources) and role-based documentation identifying who is responsible for maintaining these systems as part of an overall CMMC Level 2 compliance approach.
Common Gaps to Avoid
Common issues include having no formal documentation of which systems generate timestamps, unclear coverage for cloud services or appliances, and inconsistent timestamp behavior across platforms.
FAQ
What does AU.L2-3.3.4[a] require?
It requires identifying which systems are responsible for generating timestamps in audit records so event timing can be consistently understood and validated.
Why is it important to know which systems generate timestamps?
Knowing the timestamp sources supports reliable event correlation and incident investigation by reducing ambiguity about when actions occurred across different systems.
What evidence can support this objective during an assessment?
Common evidence includes an inventory of log-producing systems, documentation showing which components timestamp events, and records of time configuration and responsible roles.