BSI C5:2020·Criterion OPS-21·high·Component: Operations Security

What this control requires

Periodically informs customers of incident status and involves them in resolution per contractual agreements. Notifies customers of resolved incidents and actions taken, ensuring transparency and maintaining trust in cloud data security.
— BSI C5:2020, Criterion OPS-21

In plain English

Periodically informs customers of incident status and involves them in resolution per contractual agreements. In practice, this means you can prove you security agreements-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-21) and look for objective evidence on the latest two assessment cycles.

How to implement

Incident Response

Runbook. Maintain a runbook keyed by incident type with named roles (IC, comms, scribe), an out-of-band comms channel, and a 72-hour timeline for external notification.

Tabletop. Run a quarterly tabletop exercise (ransomware, insider, supply-chain) and feed gaps back into the runbook.

Cloud Posture

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

Logging Monitoring

AWS. Org-trail CloudTrail to a central log archive account, GuardDuty in every region, and Security Hub for cross-source correlation.

Azure. Pipe every diagnostic setting into a central Log Analytics workspace; onboard Microsoft Sentinel for SIEM/SOAR.

GCP. Aggregate audit logs in a dedicated logging project with sink to BigQuery; enable Security Command Center Premium and route findings to Chronicle SIEM.

Operational checklist

  • Security. Document the trigger, the owner and the cadence.
  • Data. Document the trigger, the owner and the cadence.
  • Involvement. Document the trigger, the owner and the cadence.
  • Contractual. Document the trigger, the owner and the cadence.
  • Scope: agreements, management.

Evidence to collect

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

Workflow metrics (ServiceNow, Jira) show approvals and remediation. Focus: Involvement of Cloud customers in the event of incidents.

Common pitfalls

  • Runbooks that name a role but no person, or list a paging channel that no longer exists.
  • Treating CSPM findings as a backlog instead of a hot queue: findings older than the policy SLA accumulate until the auditor asks why.
  • Per-account logging that nobody stitches together at the org level — incidents that cross accounts go undetected for days.

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: incident responsechange managementcloud posturelogging monitoring