# BSI C5:2020 OIS-03 — Interfaces and Dependencies - Source: https://support.icompaas.com/compliance/bsi-c5-2020/ois-03-interfaces-and-dependencies - Section: [Compliance](https://support.icompaas.com/compliance) › [BSI C5:2020 (Cloud Computing Compliance Criteria)](https://support.icompaas.com/compliance/bsi-c5-2020) › Information Security Governance (OIS) - Last updated: 2026-06-05 - Publisher: iCompaas, Inc. (https://www.icompaas.com) **BSI C5:2020**·Criterion `OIS-03`·high·Component: **Information Security Governance** ## What this control requires > Documents and communicates interfaces and dependencies between CSP and third-party activities, covering vulnerabilities, incidents, and malfunctions. Specifies roles, responsibilities, and cooperation obligations in guidelines and contracts, ensuring timely communication of changes to enable organizational and technical responses. > > — BSI C5:2020, Criterion OIS-03 ### In plain English Documents and communicates interfaces and dependencies between CSP and third-party activities, covering vulnerabilities, incidents, and malfunctions. In practice, this means you can prove you information changes-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 **Information Security Governance**, the assessor will trace your implementation back to the catalogue reference (Criterion OIS-03) and look for objective evidence on the latest two assessment cycles. ## How to implement #### Vulnerability Management **Scanners.** Pair an unauthenticated scanner (Nessus / Qualys / Tenable.io) for external surface with an authenticated agent for OS/library CVEs on every host. **SLA.** Document remediation SLAs by CVSS / EPSS: critical 7 days, high 30 days, medium 90 days; report monthly trend to leadership. **Containers.** Scan images in CI (Trivy / Grype / Snyk Container) AND at runtime; block deploys on critical findings without exception. ### Operational checklist - **Information.** Document the trigger, the owner and the cadence. - **Interfaces.** Document the trigger, the owner and the cadence. - **Risk.** Document the trigger, the owner and the cadence. - **Security.** Document the trigger, the owner and the cadence. - **Technical.** Document the trigger, the owner and the cadence. - **Scope:** changes, management. ## Evidence to collect - **Vendor Risk Management.** `vendor_risk_management` evidence Third-party risk management evidence (assessments, contracts, due diligence) shows supplier oversight. Focus: Interfaces and Dependencies. ## Common pitfalls - 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. - [**SOC 2 (2017 TSC) CC9.2** — Vendor Risk Management](https://support.icompaas.com/compliance/soc-2-trust-services-criteria/cc9-2-vendor-risk-management) - [**CIS Controls v8 16.5** — Use Up-to-Date and Trusted Third-Party Software Components](https://support.icompaas.com/compliance/cis-controls-v8/16-5-use-up-to-date-and-trusted-third-party-software-components) - [**ISO/IEC 27001:2022 A.5.20** — Addressing information security within supplier agreements](https://support.icompaas.com/compliance/iso-27001-2022/a-5-20-addressing-information-security-within-supplier-agreements) - [**GDPR Article 76** — Confidentiality](https://support.icompaas.com/compliance/gdpr/article-76-confidentiality) - [**NIST SP 800-171 Rev. 3 3.16.2** — Unsupported System Components](https://support.icompaas.com/compliance/nist-sp-800-171-rev-3/3-16-2-unsupported-system-components) ## Related controls in BSI C5:2020 - [**Criterion COS-02** — Security requirements for connections in the Cloud Service Provider's network](https://support.icompaas.com/compliance/bsi-c5-2020/cos-02-security-requirements-for-connections-in-the-cloud-service-provider-s-network) - [**Criterion PS-01** — Physical Security and Environmental Control Requirements](https://support.icompaas.com/compliance/bsi-c5-2020/ps-01-physical-security-and-environmental-control-requirements) - [**Criterion OIS-07** — Application of the Risk Management Policy](https://support.icompaas.com/compliance/bsi-c5-2020/ois-07-application-of-the-risk-management-policy) - [**Criterion COS-03** — Monitoring of connections in the Cloud Service Provider's network](https://support.icompaas.com/compliance/bsi-c5-2020/cos-03-monitoring-of-connections-in-the-cloud-service-provider-s-network) - [**Criterion SSO-01** — Policies and instructions for controlling and monitoring third parties](https://support.icompaas.com/compliance/bsi-c5-2020/sso-01-policies-and-instructions-for-controlling-and-monitoring-third-parties) - [**Criterion SSO-03** — Directory of service providers and suppliers](https://support.icompaas.com/compliance/bsi-c5-2020/sso-03-directory-of-service-providers-and-suppliers) ## References - [Bundesamt für Sicherheit in der Informationstechnik (BSI) — BSI C5:2020](https://www.bsi.bund.de/EN/Topics/CloudComputing/Compliance_Criteria_Catalogue/Compliance_Criteria_Catalogue_node.html) - Catalogue identifier: `Criterion OIS-03` Topics: vendor riskvendor managementsupply chain securitythird party monitoringvulnerability management ## Related compliance guidance - [SOC 2 compliance: a practical implementation guide for cloud-native SaaS teams](https://support.icompaas.com/compliance/soc-2-trust-services-criteria): Configuration checks like this one are the technical half of a SOC 2 / ISO 27001 programme — the guide shows where they fit, what else an auditor expects, and how to evidence them. - [ISO/IEC 27001:2022 compliance: a practical implementation guide](https://support.icompaas.com/compliance/iso-27001-2022): ISO 27001 Annex A.8 (technological controls) is where cloud hardening evidence lands; the guide shows how to run the ISMS around it.