ISO 27001:2022 Annex A Control 8.17

Clock Synchronisation

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It is critical to have precise, synchronised time across all an organisation’s information systems.

Not only is this necessary to maintain business operations, but it is also invaluable when dealing with ICT-related incidents.

Accurate time representation provides an organisation with the capacity to give a reliable record of how data has been managed and the activities of its staff and vendors to itself and any law enforcement or regulatory agencies.

Purpose of ISO 27001:2022 Annex A 8.17

ISO 27001:2022 Annex A 8.17 serves a dual purpose by maintaining risk through the implementation of controls to maintain accurate and reliable synchronisation of information system clocks. This helps in both internal and external investigations, as well as incident monitoring.

Ownership of Annex A 8.17

ISO 27001:2022 Annex A 8.17 is focused on technical issues, such as external data sources (e.g. atomic clocks) connected to an organisation’s ICT infrastructure.

The Head of IT should own the responsibility for maintaining the integrity and effectiveness of an organisation’s ICT infrastructure on a daily basis.

Guidance on ISO 27001:2022 Annex A 8.17

Annex A Control 8.17 refrains from proposing a step-by-step approach to managing system clocks, instead providing broad direction on how to utilise reliable reference points.

Organisations should establish a standard reference time that can be relied on for all their commercial, logistical, and maintenance-oriented systems. This is in accordance with Annex A 8.17.

Organisations should:

  1. Draft internal and external requirements for three aspects of clock synchronisation:
    • Reliable synchronisation
    • Time representation
    • Accuracy

  2. Organisations should address said requirements from six different angles:
    • Contractual
    • Standards
    • Internal monitoring
    • Legal
    • Statutory
    • Regulatory

  3. Utilise a radio time broadcast linked to an atomic clock as the single reference point, whilst implementing key protocols (NTP, PTP) to guarantee uniformity throughout the network.
  4. It is worth considering the benefits of having two distinct time sources to improve redundancy.

Guidance on Hybrid Setups

Organisations often employ both on-site and cloud-based systems side-by-side.

Cloud-hosted software and infrastructure platforms are typically managed by the vendor themselves, utilising an independent time source from the organisation’s own infrastructure.

Regularly check for any discrepancies between managed and unmanaged hardware and systems, and document any variations to avoid confusion in future enquiries.

Changes and Differences from ISO 27001:2013

ISO 27001:2022 Annex A 8.17 supersedes ISO 27001:2013 Annex A 12.4.4 (Clock Synchronisation).

ISO 27001:2022 Annex A 8.17 echoes much of the same data found in its 2013 predecessor, except for one salient point – it gives guidance on managing time sources from public and private clouds, as well as the implications of using systems on-site that may be synced to a different time source.

Table of All ISO 27001:2022 Annex A Controls

In the table below you’ll find more information on each individual ISO 27001:2022 Annex A Control.

ISO 27001:2022 Organisational Controls

Annex A Control TypeISO/IEC 27001:2022 Annex A IdentifierISO/IEC 27001:2013 Annex A IdentifierAnnex A Name
Organisational ControlsAnnex A 5.1Annex A 5.1.1
Annex A 5.1.2
Policies for Information Security
Organisational ControlsAnnex A 5.2Annex A 6.1.1Information Security Roles and Responsibilities
Organisational ControlsAnnex A 5.3Annex A 6.1.2Segregation of Duties
Organisational ControlsAnnex A 5.4Annex A 7.2.1Management Responsibilities
Organisational ControlsAnnex A 5.5Annex A 6.1.3Contact With Authorities
Organisational ControlsAnnex A 5.6Annex A 6.1.4Contact With Special Interest Groups
Organisational ControlsAnnex A 5.7NEWThreat Intelligence
Organisational ControlsAnnex A 5.8Annex A 6.1.5
Annex A 14.1.1
Information Security in Project Management
Organisational ControlsAnnex A 5.9Annex A 8.1.1
Annex A 8.1.2
Inventory of Information and Other Associated Assets
Organisational ControlsAnnex A 5.10Annex A 8.1.3
Annex A 8.2.3
Acceptable Use of Information and Other Associated Assets
Organisational ControlsAnnex A 5.11Annex A 8.1.4Return of Assets
Organisational ControlsAnnex A 5.12Annex A 8.2.1Classification of Information
Organisational ControlsAnnex A 5.13Annex A 8.2.2Labelling of Information
Organisational ControlsAnnex A 5.14Annex A 13.2.1
Annex A 13.2.2
Annex A 13.2.3
Information Transfer
Organisational ControlsAnnex A 5.15Annex A 9.1.1
Annex A 9.1.2
Access Control
Organisational ControlsAnnex A 5.16Annex A 9.2.1Identity Management
Organisational ControlsAnnex A 5.17Annex A 9.2.4
Annex A 9.3.1
Annex A 9.4.3
Authentication Information
Organisational ControlsAnnex A 5.18Annex A 9.2.2
Annex A 9.2.5
Annex A 9.2.6
Access Rights
Organisational ControlsAnnex A 5.19Annex A 15.1.1Information Security in Supplier Relationships
Organisational ControlsAnnex A 5.20Annex A 15.1.2Addressing Information Security Within Supplier Agreements
Organisational ControlsAnnex A 5.21Annex A 15.1.3Managing Information Security in the ICT Supply Chain
Organisational ControlsAnnex A 5.22Annex A 15.2.1
Annex A 15.2.2
Monitoring, Review and Change Management of Supplier Services
Organisational ControlsAnnex A 5.23NEWInformation Security for Use of Cloud Services
Organisational ControlsAnnex A 5.24Annex A 16.1.1Information Security Incident Management Planning and Preparation
Organisational ControlsAnnex A 5.25Annex A 16.1.4Assessment and Decision on Information Security Events
Organisational ControlsAnnex A 5.26Annex A 16.1.5Response to Information Security Incidents
Organisational ControlsAnnex A 5.27Annex A 16.1.6Learning From Information Security Incidents
Organisational ControlsAnnex A 5.28Annex A 16.1.7Collection of Evidence
Organisational ControlsAnnex A 5.29Annex A 17.1.1
Annex A 17.1.2
Annex A 17.1.3
Information Security During Disruption
Organisational ControlsAnnex A 5.30NEWICT Readiness for Business Continuity
Organisational ControlsAnnex A 5.31Annex A 18.1.1
Annex A 18.1.5
Legal, Statutory, Regulatory and Contractual Requirements
Organisational ControlsAnnex A 5.32Annex A 18.1.2Intellectual Property Rights
Organisational ControlsAnnex A 5.33Annex A 18.1.3Protection of Records
Organisational ControlsAnnex A 5.34 Annex A 18.1.4Privacy and Protection of PII
Organisational ControlsAnnex A 5.35Annex A 18.2.1Independent Review of Information Security
Organisational ControlsAnnex A 5.36Annex A 18.2.2
Annex A 18.2.3
Compliance With Policies, Rules and Standards for Information Security
Organisational ControlsAnnex A 5.37Annex A 12.1.1Documented Operating Procedures

ISO 27001:2022 People Controls

Annex A Control TypeISO/IEC 27001:2022 Annex A IdentifierISO/IEC 27001:2013 Annex A IdentifierAnnex A Name
People ControlsAnnex A 6.1Annex A 7.1.1Screening
People ControlsAnnex A 6.2Annex A 7.1.2Terms and Conditions of Employment
People ControlsAnnex A 6.3Annex A 7.2.2Information Security Awareness, Education and Training
People ControlsAnnex A 6.4Annex A 7.2.3Disciplinary Process
People ControlsAnnex A 6.5Annex A 7.3.1Responsibilities After Termination or Change of Employment
People ControlsAnnex A 6.6Annex A 13.2.4Confidentiality or Non-Disclosure Agreements
People ControlsAnnex A 6.7Annex A 6.2.2Remote Working
People ControlsAnnex A 6.8Annex A 16.1.2
Annex A 16.1.3
Information Security Event Reporting

ISO 27001:2022 Physical Controls

Annex A Control TypeISO/IEC 27001:2022 Annex A IdentifierISO/IEC 27001:2013 Annex A IdentifierAnnex A Name
Physical ControlsAnnex A 7.1Annex A 11.1.1Physical Security Perimeters
Physical ControlsAnnex A 7.2Annex A 11.1.2
Annex A 11.1.6
Physical Entry
Physical ControlsAnnex A 7.3Annex A 11.1.3Securing Offices, Rooms and Facilities
Physical ControlsAnnex A 7.4NEWPhysical Security Monitoring
Physical ControlsAnnex A 7.5Annex A 11.1.4Protecting Against Physical and Environmental Threats
Physical ControlsAnnex A 7.6Annex A 11.1.5Working In Secure Areas
Physical ControlsAnnex A 7.7Annex A 11.2.9Clear Desk and Clear Screen
Physical ControlsAnnex A 7.8Annex A 11.2.1Equipment Siting and Protection
Physical ControlsAnnex A 7.9Annex A 11.2.6Security of Assets Off-Premises
Physical ControlsAnnex A 7.10Annex A 8.3.1
Annex A 8.3.2
Annex A 8.3.3
Annex A 11.2.5
Storage Media
Physical ControlsAnnex A 7.11Annex A 11.2.2Supporting Utilities
Physical ControlsAnnex A 7.12Annex A 11.2.3Cabling Security
Physical ControlsAnnex A 7.13Annex A 11.2.4Equipment Maintenance
Physical ControlsAnnex A 7.14Annex A 11.2.7Secure Disposal or Re-Use of Equipment

ISO 27001:2022 Technological Controls

Annex A Control TypeISO/IEC 27001:2022 Annex A IdentifierISO/IEC 27001:2013 Annex A IdentifierAnnex A Name
Technological ControlsAnnex A 8.1Annex A 6.2.1
Annex A 11.2.8
User Endpoint Devices
Technological ControlsAnnex A 8.2Annex A 9.2.3Privileged Access Rights
Technological ControlsAnnex A 8.3Annex A 9.4.1Information Access Restriction
Technological ControlsAnnex A 8.4Annex A 9.4.5Access to Source Code
Technological ControlsAnnex A 8.5Annex A 9.4.2Secure Authentication
Technological ControlsAnnex A 8.6Annex A 12.1.3Capacity Management
Technological ControlsAnnex A 8.7Annex A 12.2.1Protection Against Malware
Technological ControlsAnnex A 8.8Annex A 12.6.1
Annex A 18.2.3
Management of Technical Vulnerabilities
Technological ControlsAnnex A 8.9NEWConfiguration Management
Technological ControlsAnnex A 8.10NEWInformation Deletion
Technological ControlsAnnex A 8.11NEWData Masking
Technological ControlsAnnex A 8.12NEWData Leakage Prevention
Technological ControlsAnnex A 8.13Annex A 12.3.1Information Backup
Technological ControlsAnnex A 8.14Annex A 17.2.1Redundancy of Information Processing Facilities
Technological ControlsAnnex A 8.15Annex A 12.4.1
Annex A 12.4.2
Annex A 12.4.3
Logging
Technological ControlsAnnex A 8.16NEWMonitoring Activities
Technological ControlsAnnex A 8.17Annex A 12.4.4Clock Synchronization
Technological ControlsAnnex A 8.18Annex A 9.4.4Use of Privileged Utility Programs
Technological ControlsAnnex A 8.19Annex A 12.5.1
Annex A 12.6.2
Installation of Software on Operational Systems
Technological ControlsAnnex A 8.20Annex A 13.1.1Networks Security
Technological ControlsAnnex A 8.21Annex A 13.1.2Security of Network Services
Technological ControlsAnnex A 8.22Annex A 13.1.3Segregation of Networks
Technological ControlsAnnex A 8.23NEWWeb filtering
Technological ControlsAnnex A 8.24Annex A 10.1.1
Annex A 10.1.2
Use of Cryptography
Technological ControlsAnnex A 8.25Annex A 14.2.1Secure Development Life Cycle
Technological ControlsAnnex A 8.26Annex A 14.1.2
Annex A 14.1.3
Application Security Requirements
Technological ControlsAnnex A 8.27Annex A 14.2.5Secure System Architecture and Engineering Principles
Technological ControlsAnnex A 8.28NEWSecure Coding
Technological ControlsAnnex A 8.29Annex A 14.2.8
Annex A 14.2.9
Security Testing in Development and Acceptance
Technological ControlsAnnex A 8.30Annex A 14.2.7Outsourced Development
Technological ControlsAnnex A 8.31Annex A 12.1.4
Annex A 14.2.6
Separation of Development, Test and Production Environments
Technological ControlsAnnex A 8.32Annex A 12.1.2
Annex A 14.2.2
Annex A 14.2.3
Annex A 14.2.4
Change Management
Technological ControlsAnnex A 8.33Annex A 14.3.1Test Information
Technological ControlsAnnex A 8.34Annex A 12.7.1Protection of Information Systems During Audit Testing

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