A.8.20 A.8 · Technological Controls

A.8.20 — Networks security

Manage, control and protect the organisation's networks and network devices against threats.

Also written as A8.20, Annex A 8.20, ISO 27001:2022 A.8.20, ISO27001 A.8.20.

Written by Jett N. · Last reviewed

What ISO 27001 A.8.20 requires

Networks security is one of 34 Technological Controls in ISO/IEC 27001:2022 Annex A. Manage, control and protect the organisation's networks and network devices against threats. Technological controls are tested against system state, not policy text: expect the auditor to ask for configuration exports, tickets, or console screenshots showing the control is enforced in the live environment.

Audit evidence assessors look for

When preparing your Statement of Applicability (SoA) for A.8.20, gather artefacts such as:

  • Network security policy and architecture documentation
  • Firewall ruleset reviews (at least semi-annual)
  • Network security assessment or penetration test reports
  • Network device hardening configuration evidence

How A.8.20 maps to SOC 2 and NIST CSF

If you run more than one framework, the same evidence usually satisfies all of them. A.8.20 aligns with:

SOC 2: CC6.6 Protection against external threats

NIST CSF 2.0: PR.IR-01 Network protection from unauthorized access, DE.CM-01 Network monitoring

ISO 27001:2013 mapping

A.8.20 consolidates the following ISO 27001:2013 control(s): A.13.1.1. If you are transitioning an existing ISMS, map your prior evidence for these to A.8.20 in your updated SoA.

Map A.8.20 to NIST CSF & SOC 2 →
Crosswalk this control in the Control Mapper & Gap Assessment.
Document the risk →
Record treatment for gaps against A.8.20 in the Risk Register.

Related Annex A controls

A.6.7 Remote working A.8.21 Security of network services A.8.22 Segregation of networks A.8.23 Web filtering A.8.27 Secure system architecture and engineering principles A.8.31 Separation of development, test and production environments

See all 34 Technological Controls →

Frequently asked questions

Is ISO 27001 A.8.20 mandatory?

Annex A controls are not mandatory in the abstract. Clause 6.1.3 requires you to compare your risk treatment plan against Annex A and justify, in the Statement of Applicability, any control you exclude. If your risk assessment surfaces a risk that A.8.20 addresses, excluding it needs a documented, risk-based rationale that an auditor will test.

How do auditors test ISO 27001 A.8.20?

In two passes. First design: does a documented control exist, is it owned, and does it address the risk? Then operating effectiveness: the auditor samples records from across the audit period to confirm the control actually ran. A Stage 2 audit will typically pull several samples, so evidence that only exists for the month before the audit is a common finding.

How often should A.8.20 be reviewed?

ISO 27001 sets no fixed interval — it requires review at "planned intervals" and after significant change. Annual review is the norm most certification bodies expect, with an out-of-cycle review triggered by incidents, major system changes, restructures, or new regulatory obligations. Record the review date and outcome either way; an undated control is treated as unreviewed.

What does ISO 27001 A.8.20 map to in SOC 2 and NIST CSF?

A.8.20 aligns with SOC 2 CC6.6 and NIST CSF PR.IR-01, DE.CM-01. Evidence gathered for one framework will usually satisfy the others, which is the basis for a test-once, satisfy-many control library.

What was A.8.20 in ISO 27001:2013?

A.8.20 consolidates 1 control(s) from the 2013 edition: A.13.1.1. When transitioning, re-point the existing evidence rather than rebuilding it — the underlying requirement has not changed materially.