CIS Controls v8 9.5 — Implement DMARC

What this control requires

To lower the chance of spoofed or modified emails from valid domains, implement DMARC policy and verification, starting with implementing the Sender Policy Framework (SPF) and the DomainKeys Identified Mail (DKIM) standards.

In plain English

To lower the chance of spoofed or modified emails from valid domains, implement DMARC policy and verification, starting with implementing the Sender Policy Framework (SPF) and the DomainKeys Identified Mail (DKIM) standards. In practice, this means you can prove you implement dmarc-level controls on a defined cadence.

Why it matters

The CIS Controls are an industry-vetted, prioritised defence: skipping a safeguard widens the attack surface that the safeguards above and below it assume is closed. Audit frameworks (FedRAMP, PCI DSS, HIPAA) all cite CIS as evidence of due care.

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

A CIS-aligned reviewer wants to see (a) which Implementation Group you are targeting, (b) a documented owner for the safeguard, and (c) a tooling or process artefact (config, scan output, ticket) that proves the safeguard runs on the cadence the control demands.

Within Protect, the assessor will trace your implementation back to the catalogue reference (Control 9.5) and look for objective evidence on the latest two assessment cycles.

How to implement

Policy Management

Docs. Keep each policy in version-controlled Markdown alongside the code that implements it; ship a signed PDF snapshot at each annual review and link the SHA into the SoA.

Operational checklist

• Implement. Document the trigger, the owner and the cadence.
• Protect. Document the trigger, the owner and the cadence.
• Scope: dmarc, emails.

Evidence to collect

• Policy Document. A signed and version-controlled policy / standard / procedure document.
• Infra Scan. Continuous infrastructure-posture telemetry — AWS Config, Azure Policy compliance, GCP Organisation Policy, Wiz / Prisma findings.

Signed policy or standard documents the safeguard. Focus: Implement DMARC.

Common pitfalls

• Policies that no engineer has read; the version in Confluence drifts from the version that's actually being enforced.

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.

• ISO/IEC 27001:2022 A.5.5 — Contact with authorities
• SOC 2 (2017 TSC) CC2.3 — External Communication on Internal Control Matters
• GDPR Article 83 — General conditions for imposing administrative fines
• ISO/IEC 27701:2025 A.3.15 — Independent review

Related controls in CIS Controls v8

• Control 2.6 — Allowlist Authorized Libraries
• Control 16.6 — Establish and Maintain a Severity Rating System and Process for Application Vulnerabilities
• Control 17.3 — Establish and Maintain an Enterprise Process for Reporting Incidents
• Control 3.5 — Securely Dispose of Data
• Control 7.1 — Establish and Maintain a Vulnerability Management Process
• Control 14.7 — Train Workforce on How to Identify and Report if Their Enterprise Assets are Missing Security Updates

References

• Center for Internet Security — CIS Controls v8
• Catalogue identifier: Control 9.5

Topics: governance riskpolicy management