A.8.21 Security of network services
For each network service, the organization is to identify, put in place and monitor the security mechanisms, the service levels and the requirements that apply. Purpose (stated in ISO/IEC 27002:2022): keeps the use of network services secure. As an Annex A reference control, it is compared with the controls determined in risk treatment (6.1.3 c) and recorded in the Statement of Applicability as included or excluded, with the justification and implementation status (6.1.3 d); implementation guidance is ISO/IEC 27002:2022 8.21.
Source: ISO/IEC 27001:2022, A.8.21. The statement above is our statement of the clause, read from the published text and cited so you can check it against the official text, not the instrument verbatim. Open ISO/IEC 27001:2022 in the compliance library.
Clauses 4 to 10 are the management-system requirements: none of them can be excluded when an organisation claims conformity. The 93 Annex A controls are a reference set: one may be excluded with a justification in the Statement of Applicability. Certification bodies assess conformity; the evidence lists here are what auditors commonly ask for, not a list the standard prescribes.
These are the artefacts auditors commonly ask for on this requirement, our guidance rather than text from the standard. Your assessor decides what is sufficient in your context, and asks for samples across the period when a report covers one.
system holds itEvidence a system already holds
- Monitoring reports on provider performance against agreed security and service levels · SIEM / log platform
- Documented rules on permitted networks and services, authentication, authorization, means of access (VPN, wireless) and contextual conditions · Identity provider / directory
periodic reviewEvidence produced at each review
- Right-to-audit clauses and third-party attestations from network and managed security service providers, with records of review · Vendor register / contract repository
governing documentDocuments that govern the control
- Statement of Applicability entry for control A.8.21, showing inclusion or justified exclusion, implementation status and the risks it treats · Policy repository / GRC workspace
- Service agreements with internal and external network providers specifying security features, service levels and requirements · Vendor register / contract repository
First move
Common gaps auditors find
- Network service contracts specify bandwidth and uptime but no security requirements
- Managed security providers are never audited and attestation reports are not reviewed
- No rules define which networks users may connect to or how
- CDN caching settings expose confidential content
Do this for your whole sheet
Paste the rows you run your controls from and get this mapping for every control at once, with the periodic-review ones flagged and a first move per row. No account for the first run.
Build my evidence sheet