ISO/IEC 27001:2022 · Technological control
ISO 27001 Annex A 8.17: Clock synchronization
Quick answer
ISO 27001 Annex A 8.17 (Clock synchronization) is a technological control. Synchronise system clocks to approved time sources so logs line up during investigations.
What auditors look for
Auditors check that 8.17 is either justified as not applicable in your Statement of Applicability or implemented and working. Typical evidence includes:
- Time source configuration
- Checks of clock drift
- Standard time zone for logs
How to implement 8.17 in practice
- Use reliable NTP sources
- Log in UTC
- Check cloud and on-premises systems match
- Name an owner for 8.17, decide how often it runs and file evidence each time, so the control is audit-ready all year.
Recording 8.17 in the Statement of Applicability
List 8.17 with whether it applies, the reason (usually the risks it treats or a legal or contractual requirement), its implementation status and where the evidence lives. If you exclude it, explain why none of your risks or obligations require it.