AU-8

AU-8 TIME STAMPS

Overview

Number	Title	Impact	Priority	Subject Area
AU-8	Time Stamps	LOW	P1	Audit And Accountability

Instructions
The information system: AU-8a. Uses internal system clocks to generate time stamps for audit records; and AU-8b. Records time stamps for audit records that can be mapped to Coordinated Universal Time (UTC) or Greenwich Mean Time (GMT) and meets Assignment: organization-defined granularity of time measurement.

Guidance
Time stamps generated by the information 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 information system clocks and reference clocks, for example, clocks synchronizing within hundreds of milliseconds or within tens of milliseconds. Organizations may define different time granularities for different system components. Time service can also 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.

Guidance

Time stamps generated by the information 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 information system clocks and reference clocks, for example, clocks synchronizing within hundreds of milliseconds or within tens of milliseconds. Organizations may define different time granularities for different system components. Time service can also 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.

Enhancements

AU-8 (1) Synchronization With Authoritative Time Source

MODERATE

This control enhancement provides uniformity of time stamps for information systems with multiple system clocks and systems connected over a network.

The information system:

AU-8 (1)(a)

Compares the internal information system clocks Assignment: organization-defined frequency with Assignment: organization-defined authoritative time source; and

AU-8 (1)(b)

Synchronizes the internal system clocks to the authoritative time source when the time difference is greater than Assignment: organization-defined time period.

AU-8 (2) Secondary Authoritative Time Source

The information system identifies a secondary authoritative time source that is located in a different geographic region than the primary authoritative time source.