SC-45 System Time Synchronization
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Title
System Time Synchronization
Control
Synchronize system clocks within and between systems and system components.
Discussion
Time synchronization of system clocks is essential for the correct execution of many system services, including identification and authentication processes that involve certificates and time-of-day restrictions as part of access control. Denial of service or failure to deny expired credentials may result without properly synchronized clocks within and between systems and system components. 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. The granularity of time measurements refers to the degree of synchronization between system clocks and reference clocks, such as clocks synchronizing within hundreds of milliseconds or tens of milliseconds. Organizations may define different time granularities for 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 the capabilities.
Related controls
ac-3, au-8, ia-2, ia-8
Assessment objective
SC-45 system clocks are synchronized within and between systems and system components.
STIG rules that implement this control 8
Apple macOS 15 (Sequoia) V1R8
- APPL-15-000014 CAT II The macOS system must enforce time synchronization.
- APPL-15-000180 CAT II The macOS system must enable the time synchronization daemon.
Apple macOS 26 (Tahoe) V1R4
- APPL-26-000014 CAT II The macOS system must enforce time synchronization.
- APPL-26-000180 CAT II The macOS system must enable the time synchronization daemon.
Canonical Ubuntu 24.04 LTS V1R7
- UBTU-24-600160 CAT III Ubuntu 24.04 LTS must compare internal information system clocks at least every 24 hours with an authoritative time server.
Cisco IOS XE Router NDM Y26M04
- CISC-ND-001030 CAT II The Cisco router must be configured to synchronize its clock with the primary and secondary time sources using redundant authoritative time sources.
Microsoft Windows Server 2025 V1R4
- WN25-00-000440 CAT III The Windows Server 2025 time service must synchronize with an appropriate DoW time source.
Red Hat Enterprise Linux 10 V1R3
- RHEL-10-800040 CAT II RHEL 10 must securely compare internal information system clocks at least every 24 hours.