BSI C5:2020 OIS-04 — Segregation of Duties

What this control requires

Separates conflicting tasks based on OIS-06 risk assessment to prevent unauthorized changes or misuse of cloud customer data. Covers rights administration, development/testing, and system operations. Implements monitoring measures when separation is infeasible to detect and address unauthorized activities promptly.

In plain English

Separates conflicting tasks based on OIS-06 risk assessment to prevent unauthorized changes or misuse of cloud customer data. In practice, this means you can prove you information measures-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-04) 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

• Information. Document the trigger, the owner and the cadence.
• Segregation. Document the trigger, the owner and the cadence.
• Risk. Document the trigger, the owner and the cadence.
• Review. Document the trigger, the owner and the cadence.
• Security. Document the trigger, the owner and the cadence.
• Scope: measures, cloud customer data, administration, development, changes, management.

Evidence to collect

• Identity Scan. IAM / IdP exports — Entra ID, Okta, IAM Identity Center, Workspace directory — showing accounts, roles, MFA state and last sign-in.

Identity analytics (Okta, SailPoint, Access Analyzer) demonstrates least-privilege. Focus: Segregation of Duties.

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.

• NIST SP 800-171 Rev. 3 3.3.1 — Event Logging
• SOC 2 (2017 TSC) CC6.2 — Access Provisioning
• ISO/IEC 27001:2022 A.8.2 — Privileged access rights
• CIS Controls v8 14.9 — Conduct Role-Specific Security Awareness and Skills Training
• NIST SP 800-53 Rev. 5 AC-6(6) — Privileged Access By Non-Organizational Users

Related controls in BSI C5:2020

• Criterion IDM-06 — Privileged access rights
• Criterion DEV-07 — Logging of changes
• Criterion IDM-04 — Withdraw or adjust access rights as the task area changes
• Criterion PSS-09 — Authorisation Mechanisms
• Criterion AM-05 — Commitment to Permissible Use, Safe Handling and Return of Assets
• Criterion HR-01 — Verification of qualification and trustworthiness

References

• Bundesamt für Sicherheit in der Informationstechnik (BSI) — BSI C5:2020
• Catalogue identifier: Criterion OIS-04

Topics: identity accesslogging monitoringprivileged accessidentity managementaccess reviewcloud posture