ISO/IEC 27001:2022 A.8.23 — Web filtering

What this control requires

Access to external websites shall be managed to reduce exposure to malicious content.

In plain English

Access to external websites shall be managed to reduce exposure to malicious content. In practice, this means you can prove you management management-level controls on a defined cadence.

Why it matters

ISO 27001 certification depends on showing each Annex A control is either implemented or explicitly justified for exclusion in the Statement of Applicability (SoA). Certification bodies sample controls during surveillance audits, and a missing SoA entry — or implementation that doesn't match the SoA wording — is a finding.

This control is rated high. Auditors expect a named owner, a remediation SLA, and a tooling artefact that evidences continuous operation.

What an auditor looks for

An ISO 27001 lead auditor looks for: (1) an SoA entry covering the control with justification, (2) a documented procedure or policy implementing it, (3) records that prove the procedure runs (logs, tickets, training records) and (4) management-review evidence that effectiveness is monitored.

Within Technological controls, the assessor will trace your implementation back to the catalogue reference (Annex A A.8.23) and look for objective evidence on the latest two assessment cycles.

How to implement

1. Write a short policy stating intent, scope and named owner.
2. Encode it as a platform guardrail — SCP, Azure Policy initiative, Organisation Policy, or repository policy.
3. Wire a monitoring signal that catches drift (CSPM rule, SIEM rule, scheduled query, Workspace alert) and ticket it.
4. Review on a documented cadence and capture the review in the risk register or compliance tracker.

Operational checklist

• Management. Document the trigger, the owner and the cadence.
• Identity. Document the trigger, the owner and the cadence.
• Access. Document the trigger, the owner and the cadence.
• Scope: management.

Evidence to collect

• Infra Scan. Continuous infrastructure-posture telemetry — AWS Config, Azure Policy compliance, GCP Organisation Policy, Wiz / Prisma findings.

Secure web gateway telemetry (Zscaler, Cloudflare) shows URL filtering and threat blocking policies in effect.

How it maps to other frameworks

Computed from shared tags, control component and key-operation subjects — handy when you are reconciling controls across an audit.

• SOC 2 (2017 TSC) CC1.5 — Accountability for Internal Control Responsibilities
• NIST SP 800-171 Rev. 3 3.13.4 — Information in Shared System Resources
• CIS Controls v8 9.2 — Use DNS Filtering Services
• ISO/IEC 27701:2025 A.3.8 — Identity management
• BSI C5:2020 AM-05 — Commitment to Permissible Use, Safe Handling and Return of Assets

Related controls in ISO/IEC 27001:2022

• Annex A A.8.2 — Privileged access rights
• Annex A A.5.16 — Identity management
• Annex A A.5.33 — Protection of records
• Annex A A.5.2 — Information security roles and responsibilities
• Annex A A.6.1 — Screening
• Annex A A.8.4 — Access to source code

References

• ISO/IEC JTC 1/SC 27 — ISO/IEC 27001:2022
• Catalogue identifier: Annex A A.8.23

Topics: identity accessidentity managementaccess reviewprivileged access