Overview
  1. 03.01: Access Control
  2. 03.02: Awareness and Training
  3. 03.03: Audit and Accountability
  4. 03.04: Configuration Management
  5. 03.05: Identification and Authentication
  6. 03.06: Incident Response
  7. 03.07: Maintenance
  8. 03.08: Media Protection
  9. 03.09: Personnel Security
  10. 03.10: Physical Protection
  11. 03.11: Risk Assessment
  12. 03.12: Security Assessment
  13. 03.13: System and Communications Protection
  14. 03.14: System and Information Integrity

Security Requirements for 03.03.07 Authoritative Time Source

Internal system clocks are used to generate time stamps, which include date and time. Time is 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, 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. This requirement provides uniformity of time stamps for systems with multiple system clocks and systems connected over a network. See [IETF 5905].

Assessment GuidanceExamine 0/7

How an assessor determines this requirement is met. Source: CMMC Assessment Guide – Level 2, Version 2.13 (NIST SP 800-171 Rev. 2).

Discussion

Each system must synchronize its time with a central time server to ensure that all systems are recording audit logs using the same time source. Reviewing audit logs from multiple systems can be a difficult task if time is not synchronized. Systems can be synchronized to a network device or directory service or configured manually.

Examples

  1. Example 1

    You are setting up several new computers on your company’s network, which contains CUI. You update the time settings on each machine to use the same authoritative time server on the internet [b, c]. When you review audit logs, all your machines will have synchronized time, which aids in any potential security investigations.

Assessment Methods

Examine
The process of reviewing, inspecting, observing, studying, or analyzing assessment objects (e.g., policies, procedures, plans, system designs, mechanisms) to facilitate understanding, achieve clarification, or obtain evidence.Example: An assessor reads the access control policy and inspects system configuration settings to confirm they match.

Not all of the evidence listed is required to meet this requirement — check the items your organization has collected.

Interview
The process of holding discussions with individuals or groups within an organization to facilitate understanding, achieve clarification, or identify the location of evidence.Example: An assessor asks a system administrator to describe how user accounts are approved, reviewed, and disabled.
  • Personnel with information security responsibilities
  • System or network administrators
  • System developers
Test
The process of exercising assessment objects (e.g., activities, mechanisms) under specified conditions to compare actual behavior with expected behavior.Example: An assessor attempts to sign in with a disabled account to confirm that access is denied.
  • Mechanisms implementing time stamp generation
  • Mechanisms implementing internal information system clock synchronization

Potential Assessment Considerations

  • Can the records’ time stamps map to Coordinated Universal Time (UTC), compare system clocks with authoritative Network Time Protocol (NTP) servers, and synchronize system clocks when the time difference is greater than 1 second [c]?
  • Does the system synchronize internal system clocks on a defined frequency [c]?

Key References

NIST SP 800-171 Rev. 2 3.3.7

Evidence

  1. 03.03.07.a

    Internal system clocks are used to generate time stamps for audit records

  1. 03.03.07.b

    An authoritative source with which to compare and synchronize internal system clocks is specified

  1. 03.03.07.c

    Internal system clocks used to generate time stamps for audit records are compared to and synchronized with the specified authoritative time source