CISSP GLOSSARY · SECURITY ARCHITECTURE
No Read Up (Simple Security Property)
The Bell-LaPadula rule that a subject cannot read data classified above their clearance. Confidentiality's ceiling: a Secret clearance never opens a Top Secret file.
No Read Up is the first rule of the Bell-LaPadula model, formally the Simple Security Property. A subject may read an object only if the subject’s clearance dominates the object’s classification. A Secret-cleared analyst can read Secret and below; Top Secret stays closed. The rule is intuitive, which is exactly why the exam pairs it with its stranger sibling.
That sibling is No Write Down, the Star Property, and together the two rules make confidentiality airtight: you cannot look above your level, and you cannot leak what you know to below your level. In mandatory access control terms, No Read Up is the read half of the lattice comparison the system performs on every access. The Biba model mirrors this rule as No Read Down, protecting integrity instead of confidentiality.
Exam relevance: memorise the property names with their rules, because the exam asks them by name. Simple Security Property equals No Read Up; anything “Simple” in these models governs reading, anything “Star” governs writing. Then check the model: reading restricted upward is Bell-LaPadula and confidentiality; reading restricted downward is Biba and integrity.