ISO 27001 A.8.20: network security, explained for startups

A.8.20 Networks security

Your networks are protected and only allow the traffic they need. What proves it: a network diagram and the rules that restrict traffic in and out.

A certification auditor samples network diagrams and firewall rules. A file that usually does the job: a network diagram and the production security group rules.

How to put it in place

Each step leaves a record, and the record is what the auditor samples rather than the step itself. Inside Polara, the control card for A.8.20 walks you through it in this order.

1. Draw a simple diagram of your production network.
2. Close inbound access to only what the service needs.
3. Review the rules every quarter.

The free ISO 27001 readiness assessment asks one question that evidences it:

• Do firewall or filtering rules restrict traffic?

Policies, connectors and the SOC 2 overlap

In the ISO 27001 policy pack, the Network Security Policy covers A.8.20. An auditor reads the policy for the rule, then samples the records to see the rule was followed.

The same evidence counts toward SOC 2. The Trust Services criterion that cover this ground: CC6.6, network boundaries.

Technological controls

A.8.20 is one of the 34 technological controls in Annex A. The controls built into your systems: access, devices, malware, vulnerabilities, backups, logging, networks, encryption and secure development. Exports and settings screenshots prove most of them.

Nearby controls in the same theme:

• A.8.17, clock synchronization
• A.8.18, powerful admin utilities
• A.8.19, installing software
• A.8.21, network services
• A.8.22, network segregation
• A.8.23, web filtering

Before it: A.8.19, installing software. After it: A.8.21, network services. Every control, by theme, is on the Annex A controls page.