Reference monitor
In operating systems architecture a reference monitor concept defines a set of design requirements on a reference validation mechanism, which enforces an access control policy over subjects' (e.g., processes and users) ability to perform operations (e.g., read and write) on objects (e.g., files and sockets) on a system.
- The reference validation mechanism must always be invoked (complete mediation).
- The reference validation mechanism must be tamperproof (tamperproof).
- The reference validation mechanism must be small enough to be subject to analysis and tests, the completeness of which can be assured (verifiable).
For example, Windows 3.x and 9x operating systems were not built with a reference monitor, whereas the Windows NT line, which also includes Windows 2000 and Windows XP, was designed to contain a reference monitor,[1] although it is not clear that its properties (tamperproof, etc.) have ever been independently verified, or what level of computer security it was intended to provide.
The claim is that a reference validation mechanism that satisfies the reference monitor concept will correctly enforce a system's access control policy, as it must be invoked to mediate all security-sensitive operations, must not be tampered, and has undergone complete analysis and testing to verify correctness.
The Reference Monitor concept was introduced in the Computer Security Technology Planning Study (Oct, 1972) by James Anderson & Co.
Systems evaluated at B3 and above by the Trusted Computer System Evaluation Criteria (TCSEC) must enforce the reference monitor concept.
References
See also
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