SSCP Systems Security Certified PractitionerAccess ControlsHard
A security analyst is reviewing a system that prevents users from downgrading the security classification of a document they are editing, even if they have read and write permissions at their current clearance level. This ensures that sensitive information does not accidentally or maliciously get released to a lower security domain. Which security model principle is being applied here?
- AStrong Tranquility Property
- BSimple Security Property (No Read Up)
- CDiscretionary Security Property
- D*-Property (Star Property or No Write Down)
Show answer & explanationAnswer & explanation
Correct answer: D. *-Property (Star Property or No Write Down)
The Bell-LaPadula model's *-Property (Star Property) states that a subject cannot write to an object with a lower security classification (no write down). This prevents information from flowing from a higher security level to a lower one, directly matching the scenario.
Why the other options are wrong
- A. Strong Tranquility Property states that security labels cannot change during a system's normal operation, which is a different concept.
- B. Simple Security Property (No Read Up) prevents subjects from reading objects at a higher security level.
- C. Discretionary Security Property is not a standard Bell-LaPadula property; it relates to DAC.
Bell-LaPadula *-Property (Star Property)
A rule in the Bell-LaPadula access control model that states a subject at a given security level cannot write to an object at a lower security level (also known as 'no write down').
- Prevents information flow from higher to lower classification levels.
- Crucial for maintaining confidentiality in multi-level security systems.
- Works in conjunction with the Simple Security Property ('no read up').
Memory trick: Bell-LaPadula: Don't read up, don't write down.