id: "SC-45" title: "System Time Synchronization" family: "SC" family_name: "System and Communications Protection" sort_id: "sc-45" priority: "P1" implementation_level: "system" enhancements: - sc-45.1 - sc-45.2
Statement
Synchronize system clocks within and between systems and system components.
Guidance
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.
Assessment Objective
system clocks are synchronized within and between systems and system components.
System and communications protection policy
procedures addressing time synchronization
system design documentation
system configuration settings and associated documentation
system audit records
system security plan
other relevant documents or records
System/network administrators
organizational personnel with information security responsibilities
organizational personnel installing, configuring, and/or maintaining the system
Mechanisms supporting and/or implementing system time synchronization