BSI C5:2020·Criterion OPS-23·high·Component: Operations Security

What this control requires

Hardens production environment components per industry standards, documenting requirements. Verifies immutable images for compliance, retaining configuration logs to ensure secure configurations protect cloud customer data from attacks.
— BSI C5:2020, Criterion OPS-23

In plain English

Hardens production environment components per industry standards, documenting requirements. In practice, this means you can prove you risk - configuration-level controls on a defined cadence.

Why it matters

BSI C5 is the default cloud-security baseline German public-sector buyers and many DAX-listed enterprises expect; gaps here directly block procurement in the DACH region and frequently appear as must-have items in EU public-tender documents.

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 C5 attesting auditor (under ISAE 3000 / IDW PS 860) tests both the design and — for a Type 2 — the operating effectiveness over the attestation period. For each criterion they look for both the Basic and any in-scope Additional objectives.

Within Operations Security, the assessor will trace your implementation back to the catalogue reference (Criterion OPS-23) and look for objective evidence on the latest two assessment cycles.

How to implement

Configuration Management

Policy-as-code. Codify the control as Service Control Policies (AWS), Azure Policy initiatives, or Organisation Policy (GCP) so the platform enforces what the document promises.

IaC. Gate Terraform / Pulumi / CloudFormation changes with Checkov / tfsec / OPA so misconfigurations never reach production.

Drift. Run a CSPM (Wiz / Prisma / Defender for Cloud / Security Command Center) over every account and route findings to a single risk register.

Cloud Posture

CSPM. Run Wiz / Prisma / Defender for Cloud / Security Command Center over every account; auto-ticket findings above your accepted-risk threshold.

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

  • Risk. Document the trigger, the owner and the cadence.
  • Security. Document the trigger, the owner and the cadence.
  • Data. Document the trigger, the owner and the cadence.
  • Policy. Document the trigger, the owner and the cadence.
  • Secure. Document the trigger, the owner and the cadence.
  • Scope: - configuration, cloud customer data, management.

Evidence to collect

  • Policy Document. A signed and version-controlled policy / standard / procedure document.

Signed policy or standard documents the safeguard. Focus: Managing Vulnerabilities, Malfunctions and Errors - System Hardening.

Common pitfalls

  • Manual cloud-console changes that never make it back to Terraform — drift accumulates until the next outage forces a reconciliation.
  • Treating CSPM findings as a backlog instead of a hot queue: findings older than the policy SLA accumulate until the auditor asks why.
  • Policies that no engineer has read; the version in Confluence drifts from the version that's actually being enforced.
  • Scans that hit only the perimeter; missing authenticated scans of OS, runtime libs and base images so most CVEs are invisible.

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.

Related controls in BSI C5:2020

References

Topics: governance riskconfiguration managementcloud posturepolicy managementvulnerability management