AC-25 — Reference Monitor
A reference monitor is a set of design requirements on a reference validation mechanism that, as a key component of an operating system, enforces an access control policy over all subjects and objects. A reference validation mechanism is always invoked, tamper-proof, and small enough to be subject to analysis and tests, the completeness of which can be assured (i.e., verifiable). Information is represented internally within systems using abstractions known as data structures. Internal data structures can represent different types of entities, both active and passive. Active entities, also known as subjects, are associated with individuals, devices, or processes acting on behalf of individuals. Passive entities, also known as objects, are associated with data structures, such as records, buffers, communications ports, tables, files, and inter-process pipes. Reference monitors enforce acce
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NIST CSF 2.0 informative references
These CSF Subcategories list this base control or one of its enhancements in the imported NIST informative reference.
NIST SP 800-171 and SP 800-172
SP 800-171 requirements sourcing this control
SP 800-172 enhanced requirements sourcing this control
MITRE D3FEND techniques
MITRE ATT&CK relationships
Curated mitigation mappings
Inferred behavior relationships
Experimental: These relationships are inferred through D3FEND and must be validated against architecture, telemetry, and threat context.
Use the map without overclaiming.
A CSF informative reference is not an equivalence statement. A source-control relationship is not proof of implementation. A D3FEND semantic relationship is not a product claim. An inferred ATT&CK link is a hypothesis for engineering analysis.
Bare Metal Cyber is an independent educational publisher and is not affiliated with or endorsed by NIST or MITRE. Informative references and cross-framework relationships support navigation and analysis; they do not establish compliance, applicability, equivalence, control inheritance, or guaranteed mitigation effectiveness.