- See ISO 27002:2022 Control 8.17 for more information.
- See ISO 27001:2013 Annex A 12.4.4 for more information.
ISO 27001:2022 Annex A 8.17 – Best Practices for Clock Synchronization
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.
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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:
- Draft internal and external requirements for three aspects of clock synchronisation:
- Reliable synchronisation
- Time representation
- Accuracy
- Organisations should address said requirements from six different angles:
- Contractual
- Standards
- Internal monitoring
- Legal
- Statutory
- Regulatory
- 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.
- It is worth considering the benefits of having two distinct time sources to improve redundancy.
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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.
| Annex A Control Type | ISO/IEC 27001:2022 Annex A Identifier | ISO/IEC 27001:2013 Annex A Identifier | Annex A Name |
|---|---|---|---|
| Organisational Controls | Annex A 5.1 |
Annex A 5.1.1 Annex A 5.1.2 |
Policies for Information Security |
| Organisational Controls | Annex A 5.2 | Annex A 6.1.1 | Information Security Roles and Responsibilities |
| Organisational Controls | Annex A 5.3 | Annex A 6.1.2 | Segregation of Duties |
| Organisational Controls | Annex A 5.4 | Annex A 7.2.1 | Management Responsibilities |
| Organisational Controls | Annex A 5.5 | Annex A 6.1.3 | Contact With Authorities |
| Organisational Controls | Annex A 5.6 | Annex A 6.1.4 | Contact With Special Interest Groups |
| Organisational Controls | Annex A 5.7 | NEW | Threat Intelligence |
| Organisational Controls | Annex A 5.8 |
Annex A 6.1.5 Annex A 14.1.1 |
Information Security in Project Management |
| Organisational Controls | Annex A 5.9 |
Annex A 8.1.1 Annex A 8.1.2 |
Inventory of Information and Other Associated Assets |
| Organisational Controls | Annex A 5.10 |
Annex A 8.1.3 Annex A 8.2.3 |
Acceptable Use of Information and Other Associated Assets |
| Organisational Controls | Annex A 5.11 | Annex A 8.1.4 | Return of Assets |
| Organisational Controls | Annex A 5.12 | Annex A 8.2.1 | Classification of Information |
| Organisational Controls | Annex A 5.13 | Annex A 8.2.2 | Labelling of Information |
| Organisational Controls | Annex A 5.14 |
Annex A 13.2.1 Annex A 13.2.2 Annex A 13.2.3 |
Information Transfer |
| Organisational Controls | Annex A 5.15 |
Annex A 9.1.1 Annex A 9.1.2 |
Access Control |
| Organisational Controls | Annex A 5.16 | Annex A 9.2.1 | Identity Management |
| Organisational Controls | Annex A 5.17 |
Annex A 9.2.4 Annex A 9.3.1 Annex A 9.4.3 |
Authentication Information |
| Organisational Controls | Annex A 5.18 |
Annex A 9.2.2 Annex A 9.2.5 Annex A 9.2.6 |
Access Rights |
| Organisational Controls | Annex A 5.19 | Annex A 15.1.1 | Information Security in Supplier Relationships |
| Organisational Controls | Annex A 5.20 | Annex A 15.1.2 | Addressing Information Security Within Supplier Agreements |
| Organisational Controls | Annex A 5.21 | Annex A 15.1.3 | Managing Information Security in the ICT Supply Chain |
| Organisational Controls | Annex A 5.22 |
Annex A 15.2.1 Annex A 15.2.2 |
Monitoring, Review and Change Management of Supplier Services |
| Organisational Controls | Annex A 5.23 | NEW | Information Security for Use of Cloud Services |
| Organisational Controls | Annex A 5.24 | Annex A 16.1.1 | Information Security Incident Management Planning and Preparation |
| Organisational Controls | Annex A 5.25 | Annex A 16.1.4 | Assessment and Decision on Information Security Events |
| Organisational Controls | Annex A 5.26 | Annex A 16.1.5 | Response to Information Security Incidents |
| Organisational Controls | Annex A 5.27 | Annex A 16.1.6 | Learning From Information Security Incidents |
| Organisational Controls | Annex A 5.28 | Annex A 16.1.7 | Collection of Evidence |
| Organisational Controls | Annex A 5.29 |
Annex A 17.1.1 Annex A 17.1.2 Annex A 17.1.3 |
Information Security During Disruption |
| Organisational Controls | Annex A 5.30 | NEW | ICT Readiness for Business Continuity |
| Organisational Controls | Annex A 5.31 |
Annex A 18.1.1 Annex A 18.1.5 |
Legal, Statutory, Regulatory and Contractual Requirements |
| Organisational Controls | Annex A 5.32 | Annex A 18.1.2 | Intellectual Property Rights |
| Organisational Controls | Annex A 5.33 | Annex A 18.1.3 | Protection of Records |
| Organisational Controls | Annex A 5.34 | Annex A 18.1.4 | Privacy and Protection of PII |
| Organisational Controls | Annex A 5.35 | Annex A 18.2.1 | Independent Review of Information Security |
| Organisational Controls | Annex A 5.36 |
Annex A 18.2.2 Annex A 18.2.3 |
Compliance With Policies, Rules and Standards for Information Security |
| Organisational Controls | Annex A 5.37 | Annex A 12.1.1 | Documented Operating Procedures |
| Annex A Control Type | ISO/IEC 27001:2022 Annex A Identifier | ISO/IEC 27001:2013 Annex A Identifier | Annex A Name |
|---|---|---|---|
| People Controls | Annex A 6.1 | Annex A 7.1.1 | Screening |
| People Controls | Annex A 6.2 | Annex A 7.1.2 | Terms and Conditions of Employment |
| People Controls | Annex A 6.3 | Annex A 7.2.2 | Information Security Awareness, Education and Training |
| People Controls | Annex A 6.4 | Annex A 7.2.3 | Disciplinary Process |
| People Controls | Annex A 6.5 | Annex A 7.3.1 | Responsibilities After Termination or Change of Employment |
| People Controls | Annex A 6.6 | Annex A 13.2.4 | Confidentiality or Non-Disclosure Agreements |
| People Controls | Annex A 6.7 | Annex A 6.2.2 | Remote Working |
| People Controls | Annex A 6.8 |
Annex A 16.1.2 Annex A 16.1.3 |
Information Security Event Reporting |
| Annex A Control Type | ISO/IEC 27001:2022 Annex A Identifier | ISO/IEC 27001:2013 Annex A Identifier | Annex A Name |
|---|---|---|---|
| Physical Controls | Annex A 7.1 | Annex A 11.1.1 | Physical Security Perimeters |
| Physical Controls | Annex A 7.2 |
Annex A 11.1.2 Annex A 11.1.6 |
Physical Entry |
| Physical Controls | Annex A 7.3 | Annex A 11.1.3 | Securing Offices, Rooms and Facilities |
| Physical Controls | Annex A 7.4 | NEW | Physical Security Monitoring |
| Physical Controls | Annex A 7.5 | Annex A 11.1.4 | Protecting Against Physical and Environmental Threats |
| Physical Controls | Annex A 7.6 | Annex A 11.1.5 | Working In Secure Areas |
| Physical Controls | Annex A 7.7 | Annex A 11.2.9 | Clear Desk and Clear Screen |
| Physical Controls | Annex A 7.8 | Annex A 11.2.1 | Equipment Siting and Protection |
| Physical Controls | Annex A 7.9 | Annex A 11.2.6 | Security of Assets Off-Premises |
| Physical Controls | Annex A 7.10 |
Annex A 8.3.1 Annex A 8.3.2 Annex A 8.3.3 Annex A 11.2.5 |
Storage Media |
| Physical Controls | Annex A 7.11 | Annex A 11.2.2 | Supporting Utilities |
| Physical Controls | Annex A 7.12 | Annex A 11.2.3 | Cabling Security |
| Physical Controls | Annex A 7.13 | Annex A 11.2.4 | Equipment Maintenance |
| Physical Controls | Annex A 7.14 | Annex A 11.2.7 | Secure Disposal or Re-Use of Equipment |
| Annex A Control Type | ISO/IEC 27001:2022 Annex A Identifier | ISO/IEC 27001:2013 Annex A Identifier | Annex A Name |
|---|---|---|---|
| Technological Controls | Annex A 8.1 |
Annex A 6.2.1 Annex A 11.2.8 |
User Endpoint Devices |
| Technological Controls | Annex A 8.2 | Annex A 9.2.3 | Privileged Access Rights |
| Technological Controls | Annex A 8.3 | Annex A 9.4.1 | Information Access Restriction |
| Technological Controls | Annex A 8.4 | Annex A 9.4.5 | Access to Source Code |
| Technological Controls | Annex A 8.5 | Annex A 9.4.2 | Secure Authentication |
| Technological Controls | Annex A 8.6 | Annex A 12.1.3 | Capacity Management |
| Technological Controls | Annex A 8.7 | Annex A 12.2.1 | Protection Against Malware |
| Technological Controls | Annex A 8.8 |
Annex A 12.6.1 Annex A 18.2.3 |
Management of Technical Vulnerabilities |
| Technological Controls | Annex A 8.9 | NEW | Configuration Management |
| Technological Controls | Annex A 8.10 | NEW | Information Deletion |
| Technological Controls | Annex A 8.11 | NEW | Data Masking |
| Technological Controls | Annex A 8.12 | NEW | Data Leakage Prevention |
| Technological Controls | Annex A 8.13 | Annex A 12.3.1 | Information Backup |
| Technological Controls | Annex A 8.14 | Annex A 17.2.1 | Redundancy of Information Processing Facilities |
| Technological Controls | Annex A 8.15 |
Annex A 12.4.1 Annex A 12.4.2 Annex A 12.4.3 |
Logging |
| Technological Controls | Annex A 8.16 | NEW | Monitoring Activities |
| Technological Controls | Annex A 8.17 | Annex A 12.4.4 | Clock Synchronization |
| Technological Controls | Annex A 8.18 | Annex A 9.4.4 | Use of Privileged Utility ProgramsAccess Rights |
| Technological Controls | Annex A 8.19 |
Annex A 12.5.1 Annex A 12.6.2 |
Installation of Software on Operational Systems |
| Technological Controls | Annex A 8.20 | Annex A 13.1.1 | Networks Security |
| Technological Controls | Annex A 8.21 | Annex A 13.1.2 | Security of Network Services |
| Technological Controls | Annex A 8.22 | Annex A 13.1.3 | Segregation of Networks |
| Technological Controls | Annex A 8.23 | NEW | Web filtering |
| Technological Controls | Annex A 8.24 |
Annex A 10.1.1 Annex A 10.1.2 |
Use of Cryptography |
| Technological Controls | Annex A 8.25 | Annex A 14.2.1 | Secure Development Life Cycle |
| Technological Controls | Annex A 8.26 |
Annex A 14.1.2 Annex A 14.1.3 |
Application Security Requirements |
| Technological Controls | Annex A 8.27 | Annex A 14.2.5 | Secure System Architecture and Engineering PrinciplesLearning From Information Security Incidents |
| Technological Controls | Annex A 8.28 | NEW | Secure Coding |
| Technological Controls | Annex A 8.29 |
Annex A 14.2.8 Annex A 14.2.9 |
Security Testing in Development and Acceptance |
| Technological Controls | Annex A 8.30 | Annex A 14.2.7 | Outsourced Development |
| Technological Controls | Annex A 8.31 |
Annex A 12.1.4 Annex A 14.2.6 |
Separation of Development, Test and Production Environments |
| Technological Controls | Annex A 8.32 |
Annex A 12.1.2 Annex A 14.2.2 Annex A 14.2.3 Annex A 14.2.4 |
Change Management |
| Technological Controls | Annex A 8.33 | Annex A 14.3.1 | Test Information |
| Technological Controls | Annex A 8.34 | Annex A 12.7.1 | Protection of Information Systems During Audit Testing |
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