BSI C5:2020 OPS-12 — Logging and Monitoring - Access, Storage and Deletion

What this control requires

Restricts log and metadata access to authorized users, retains data for specified periods, and deletes it when no longer needed. Implements technical procedures to ensure secure handling, protecting cloud customer data from unauthorized access.

In plain English

Restricts log and metadata access to authorized users, retains data for specified periods, and deletes it when no longer needed. In practice, this means you can prove you security - 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-12) and look for objective evidence on the latest two assessment cycles.

How to implement

Cloud Posture

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

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.

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.
• Access. Document the trigger, the owner and the cadence.
• Secure. Document the trigger, the owner and the cadence.
• Technical. Document the trigger, the owner and the cadence.
• Scope: - configuration, cloud customer data, management.

Evidence to collect

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

Infrastructure posture tooling (AWS Config, Azure Policy, Nessus) verifies platform hardening. Focus: Logging and Monitoring - Access, Storage and Deletion.

Common pitfalls

• Treating CSPM findings as a backlog instead of a hot queue: findings older than the policy SLA accumulate until the auditor asks why.
• Manual cloud-console changes that never make it back to Terraform — drift accumulates until the next outage forces a reconciliation.
• Per-account logging that nobody stitches together at the org level — incidents that cross accounts go undetected for days.
• Default-allow egress rules; East-West traffic with no segmentation; jump hosts on the public internet with password auth.

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.

• NIST SP 800-53 Rev. 5 AU-5(1) — Storage Capacity Warning
• NIST SP 800-171 Rev. 3 3.13.6 — Network Communications - Deny by Default - Allow by Exception
• CIS Controls v8 13.1 — Centralize Security Event Alerting
• ISO/IEC 27001:2022 A.5.34 — Privacy and protection of personal identifiable information (PII)
• GDPR Article 25 — Data protection by design and by default

Related controls in BSI C5:2020

• Criterion OPS-16 — Logging and Monitoring - Configuration
• Criterion OPS-02 — Capacity Management - Monitoring
• Criterion PS-07 — Surveillance of operational and environmental parameters
• Criterion OPS-24 — Separation of Datasets in the Cloud Infrastructure
• Criterion COS-04 — Cross-network access
• Criterion INQ-01 — Legal Assessment of Investigative Inquiries

References

• Bundesamt für Sicherheit in der Informationstechnik (BSI) — BSI C5:2020
• Catalogue identifier: Criterion OPS-12

Topics: logging monitoringcloud infrastructurecloud postureconfiguration managementnetwork security