Control statement
- a.Identify and document [Organization-defined: duties of individuals] ; and
- b.Define system access authorizations to support separation of duties.
Discussion
Separation of duties addresses the potential for abuse of authorized privileges and helps to reduce the risk of malevolent activity without collusion. Separation of duties includes dividing mission or business functions and support functions among different individuals or roles, conducting system support functions with different individuals, and ensuring that security personnel who administer access control functions do not also administer audit functions. Because separation of duty violations can span systems and application domains, organizations consider the entirety of systems and system components when developing policy on separation of duties. Separation of duties is enforced through the account management activities in [AC-2](#ac-2) , access control mechanisms in [AC-3](#ac-3) , and identity management activities in [IA-2](#ia-2), [IA-4](#ia-4) , and [IA-12](#ia-12).
Organization-defined parameters
These values must be resolved through the organization’s tailoring and governance process. Bracketed parameter references in the control text identify where a decision is required.
From control text to operational evidence
Use Separation of Duties as a testable risk decision. Translate the official statement into accountable people, repeatable processes, configured technology, and evidence that demonstrates the outcome over time. In this family, pay particular attention to identity, authorization, least privilege, session boundaries, and access lifecycle governance.
Implementation workflow
- Define the control boundary, responsible owner, inherited portions, and systems or processes in scope.
- Resolve each organization-defined parameter before declaring the control implemented.
- Document how the implementation satisfies every clause of the official control statement.
- Collect evidence as a normal byproduct of operation rather than only before an assessment.
- Review exceptions, changes, and monitoring results on a risk-based cadence.
Evidence examples
- access approvals and entitlement records
- role and group configuration exports
- periodic access review results
- authentication and authorization logs
Common failure patterns
- standing privileges that outlive business need
- shared or orphaned accounts
- access rules implemented differently across systems
- approvals that cannot be traced to actual permissions
Questions practitioners should ask
- What risk decision is this control intended to support in this system?
- Which parts are implemented locally, inherited, shared, or not applicable—and what evidence supports that decision?
- Do the documented narrative, deployed configuration, operating process, and collected evidence agree?
- What event or threshold requires the implementation to be reviewed or changed?
Assessment objectives and methods
Show the assessment objective
- AC-05a.[Organization-defined: duties of individuals] are identified and documented;
- AC-05b.system access authorizations to support separation of duties are defined.
Examine
- Access control policy
- procedures addressing divisions of responsibility and separation of duties
- system configuration settings and associated documentation
- list of divisions of responsibility and separation of duties
- system access authorizations
- system audit records
- system security plan
- other relevant documents or records
Interview
- Organizational personnel with responsibilities for defining appropriate divisions of responsibility and separation of duties
- organizational personnel with information security responsibilities
- system/network administrators
Test
- Mechanisms implementing separation of duties policy
Related controls
These relationships come from the official OSCAL catalog. They indicate useful dependencies or context, not automatic inheritance or equivalence.
Related defensive techniques
D3FEND maps this base control or one of its enhancements to the following defensive techniques. The ontology relation label is preserved and does not by itself prove implementation or effectiveness.
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Related NIST SP 800-171 requirements
These Rev. 3 requirements cite this base control or one of its enhancements as a source. The relationship does not by itself determine contractual applicability or complete implementation.
Authoritative sources
Bare Metal Cyber is an independent educational publisher and is not affiliated with or endorsed by NIST. Official control requirements and interpretations remain with NIST and the responsible authorizing organization.