ISO 27001 A.8.21: network services, explained for startups

A.8.21 Security of network services

Network services you use or provide are set up securely. What proves it: the network services you rely on, such as the domain name system (DNS) and load balancers, and how each is secured.

A certification auditor samples network service configuration. A file that usually does the job: load balancer settings that allow only encrypted traffic, and the account protections on your DNS provider.

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.8.21 walks you through it in this order.

1. List your network services: DNS, load balancers, content delivery and virtual private networks.
2. Secure each one: encrypted traffic only, multi-factor authentication on provider accounts and alerts on changes.
3. Review the settings once a year.

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.8.21. 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.8.21 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.8.18, powerful admin utilities
• A.8.19, installing software
• A.8.20, network security
• A.8.22, network segregation
• A.8.23, web filtering
• A.8.24, encryption

Before it: A.8.20, network security. After it: A.8.22, network segregation. Every control, by theme, is on the Annex A controls page.