Audit and Accountability 3.3.7 (3.3.7)
Provide a system capability that compares and synchronizes internal system clocks with an authoritative source to generate time stamps for audit records
Get Full GuidanceWhat Is This CMMC Control?
This control requires organizations to ensure all systems that generate audit logs use synchronized clocks that are regularly compared against an authoritative time source. This ensures that timestamps on audit records are accurate and consistent across all systems, making it possible to correlate events and reconstruct security incidents. Without synchronized time, it becomes difficult or impossible to determine the actual sequence of events during an investigation.
Control Intent
To ensure audit records have accurate, consistent, and reliable timestamps that enable effective security monitoring, incident investigation, and forensic analysis across all systems in the environment.
Who This Control Applies To
- •All systems that generate audit records or security logs
- •Network devices including routers, switches, and firewalls
- •Servers (Windows, Linux, Unix) that process or store CUI
- •Security tools including SIEM, IDS/IPS, and endpoint protection platforms
- •Database systems that log access or changes to CUI
- •Cloud-hosted systems and virtual machines
- •Authentication systems and domain controllers
- •Application servers that generate security-relevant logs
Not Applicable When
- •Systems that do not generate audit records or logs
- •Standalone systems with no network connectivity that do not process CUI
- •Systems that inherit time synchronization from a parent system or hypervisor and do not independently generate audit records
- •Air-gapped systems where time synchronization is physically impossible, provided compensating controls document time drift
Key Objectives
- 1Ensure all system clocks generating audit records are synchronized with an authoritative time source
- 2Maintain consistent time stamps across all systems to enable accurate event correlation
- 3Provide reliable temporal data for security investigations and compliance reporting
Sample Self-Assessment Questions (Partial)
Does your organization use an authoritative time source (such as NTP servers) for time synchronization?
Are all systems that generate audit logs configured to synchronize their clocks with this authoritative time source?
Implementation Approaches (High-Level)
Centralized NTP Infrastructure
Deploy internal NTP servers synchronized with authoritative external sources, with all systems configured to use internal NTP servers as their time source.
Active Directory Time Hierarchy
Windows environments use Active Directory domain hierarchy for time synchronization, with PDC Emulator synchronized to authoritative source and all domain members inheriting time from domain controllers.
Cloud-Native Time Synchronization
Cloud-hosted systems use cloud provider's managed time synchronization services, with verification that timestamps align with organizational requirements.
Hybrid Time Synchronization Architecture
Mixed environment with on-premises NTP infrastructure for local systems and cloud-native time sync for cloud resources, with centralized monitoring ensuring consistency.
GPS-Based Time Synchronization
Deploy GPS-based time appliances as authoritative time sources for high-accuracy requirements or air-gapped environments.
Evidence & Assessment Notes
Expected Evidence
Organizations should maintain documentation and evidence demonstrating compliance with this control. This may include policy documentation, configuration records, audit logs, access reviews, and other relevant artifacts that show how the control is implemented and maintained.
Plan of Action & Milestones (POA&M)
If time synchronization is not currently implemented, prioritize deployment of authoritative time sources (internal NTP servers or cloud provider services) as this is foundational for audit logging For systems with time synchronization configured but not monitored, implement monitoring and alerting for synchronization failures as an interim step If some systems cannot reach time sources due to network segmentation, document compensating controls such as manual time verification or alternative time sources For cloud migrations in progress, document plan to transition from on-premises NTP to cloud-native time synchronization with validation of consistency If acceptable time drift thresholds are not defined, establish and document thresholds as an immediate action item For systems with significant time drift, prioritize immediate synchronization and root cause analysis If time synchronization is not included in system hardening standards, update standards and apply to new systems while remediating existing systems For air-gapped or isolated systems, document alternative time synchronization methods or compensating controls for time accuracy Ensure POA&M includes specific systems affected, target synchronization accuracy, and validation method
Frequently Asked Questions
What is an authoritative time source and what qualifies as one?
An authoritative time source is a highly accurate and reliable reference for time synchronization. Common authoritative sources include NIST time servers (time.nist.gov), U.S. Naval Observatory servers, GPS-based time appliances, or internal NTP servers synchronized with these external sources. For CMMC purposes, organizations typically deploy internal NTP servers that synchronize with external authoritative sources, then configure all systems to use the internal servers.
How accurate does time synchronization need to be for CMMC compliance?
CMMC does not specify exact time accuracy requirements, but organizations should define acceptable time drift thresholds based on their operational needs. Common thresholds range from seconds to milliseconds depending on system criticality. The key requirement is that timestamps are consistent enough across systems to enable accurate event correlation during investigations. Most organizations target synchronization within 1-5 seconds for general systems and sub-second for critical security systems.
Do cloud-hosted systems need to synchronize with our on-premises time sources?
Cloud-hosted systems can use cloud provider-managed time synchronization services (such as AWS Time Sync Service or Azure Host Time) as long as the organization validates that these sources provide acceptable accuracy and consistency with on-premises systems. The critical requirement is that audit timestamps across all systems are consistent enough for event correlation, regardless of whether systems use on-premises or cloud-native time sources.
What should we do if some systems cannot reach our time synchronization servers due to network segmentation?
Systems that cannot reach time sources due to network segmentation require either network changes to allow NTP traffic (UDP port 123), deployment of time sources within the isolated segment, or documented compensating controls. Compensating controls might include manual time verification procedures, alternative time sources appropriate for the segment, or documented acceptable time drift with periodic manual correction. The key is ensuring audit timestamps remain useful for investigation purposes.
How do we verify that time synchronization is actually working and not just configured?
Verification requires checking synchronization status using system commands (such as 'ntpq -p', 'w32tm /query /status', or 'chronyc sources'), reviewing system logs for synchronization events, and implementing monitoring that alerts on synchronization failures. Organizations should also periodically compare system clocks against the authoritative source to measure actual time drift. Simply having time synchronization configured is insufficient - active synchronization must be demonstrated.
Is time synchronization required for systems that do not generate audit records?
This control specifically applies to systems that generate audit records with timestamps. Systems that do not generate audit records or security logs are not directly subject to this control. However, most systems in a CUI environment generate some form of audit records, so time synchronization is typically required broadly. Organizations should document which systems are excluded and the justification for exclusion.
How ConformatIQ Helps With CMMC Readiness
ConformatIQ is an AI-assisted CMMC readiness platform designed to help organizations prepare for assessments more efficiently. The platform supports document generation such as SSPs and POA&Ms, guided readiness workflows, centralized evidence tracking, and interview preparation for assessments.
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Request Full GuidanceInformation sourced from NIST SP 800-171 Rev. 2. See full disclaimer.