BSI C5:2020 SSO-02 — Risk assessment of service providers and suppliers

What this control requires

Conducts and annually reviews risk assessments for third parties per SSO-01, evaluating confidentiality, integrity, and dependency risks. Documents mitigation measures to ensure secure service delivery and protect cloud customer data.

In plain English

Conducts and annually reviews risk assessments for third parties per SSO-01, evaluating confidentiality, integrity, and dependency risks. In practice, this means you can prove you risk dependency-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 Supplier & Service Oversight, the assessor will trace your implementation back to the catalogue reference (Criterion SSO-02) 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.

Operational checklist

• Risk. Document the trigger, the owner and the cadence.
• Security. Document the trigger, the owner and the cadence.
• Confidentiality. Document the trigger, the owner and the cadence.
• Data. Document the trigger, the owner and the cadence.
• Secure. Document the trigger, the owner and the cadence.
• Scope: dependency, measures, cloud customer data, management.

Evidence to collect

• Vendor Risk Management. vendor_risk_management evidence

Third-party risk management evidence (assessments, contracts, due diligence) shows supplier oversight. Focus: Risk assessment of service providers and suppliers.

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.

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.

• CIS Controls v8 3.8 — Document Data Flows
• ISO/IEC 27001:2022 A.5.19 — Information security in supplier relationships
• SOC 2 (2017 TSC) CC9.2 — Vendor Risk Management
• GDPR Article 28 — Processor
• ISO/IEC 27701:2025 A.3.10 — Supplier agreements

Related controls in BSI C5:2020

• Criterion SSO-01 — Policies and instructions for controlling and monitoring third parties
• Criterion SSO-03 — Directory of service providers and suppliers
• Criterion SSO-05 — Exit strategy for the receipt of benefits
• Criterion SSO-04 — Monitoring of compliance with requirements
• Criterion COS-03 — Monitoring of connections in the Cloud Service Provider's network
• Criterion OIS-07 — Application of the Risk Management Policy

References

• Bundesamt für Sicherheit in der Informationstechnik (BSI) — BSI C5:2020
• Catalogue identifier: Criterion SSO-02

Topics: governance riskvendor riskvendor managementsupply chain securitycloud postureidentity management