ISC2 CISSP (Certified Information Systems Security Professional)Security Architecture and EngineeringEasy
A government agency is designing a new information system that handles classified documents. The system must enforce strict confidentiality, ensuring that users can only read information at or below their security clearance level, and cannot write to objects at a lower security level than their own. Which security model best fits this requirement?
- ABell-LaPadula Security Model
- BChinese Wall Security Model
- CBiba Security Model
- DClark-Wilson Security Model
Show answer & explanationAnswer & explanation
Correct answer: A. Bell-LaPadula Security Model
The Bell-LaPadula Security Model is a state machine model that enforces confidentiality. It prevents unauthorized disclosure of information by applying two primary rules: 'no read up' (a subject cannot read an object with a higher security classification) and 'no write down' (a subject cannot write to an object with a lower security classification).
Why the other options are wrong
- B. Chinese Wall prevents conflicts of interest by separating subjects from data they should not access together.
- C. Biba focuses on integrity, preventing subjects from writing to higher integrity levels or reading from lower ones.
- D. Clark-Wilson focuses on integrity by using well-formed transactions and separation of duties.
Bell-LaPadula Security Model
A state machine model focused on enforcing confidentiality, primarily used in military and government systems.
- Has two core rules: Simple Security Property (no read up) and Star (*) Property (no write down).
- Aims to prevent unauthorized disclosure of information.
- Does not address integrity directly, only confidentiality.
Memory trick: Bell-LaPadula keeps secrets locked down, like a bell in a tower.