CSSLP Question #112: Real Exam Question with Answer & Explanation

Question

Which of the following security models characterizes the rights of each subject with respect to every object in the computer system?

Options

• AClark-Wilson model
• BBell-LaPadula model
• CBiba model
• DAccess matrix

Explanation

An access matrix is a fundamental security model that precisely defines the access rights (e.g., read, write, execute) of each subject (user/process) over every object (file/resource) within a computer system. It explicitly maps permissions between subjects and objects.

Common mistakes.

• A. The Clark-Wilson model is an integrity model focused on commercial applications, emphasizing well-formed transactions and separation of duties to maintain data integrity, not directly characterizing subject-object rights for all system objects.
• B. The Bell-LaPadula model is a confidentiality-focused model that prevents unauthorized information flow from higher security levels to lower ones (no read up, no write down), but it's not a general model for characterizing all subject-object rights.
• C. The Biba model is an integrity-focused model that prevents information flow from lower integrity levels to higher ones (no read down, no write up), complementing Bell-LaPadula, but it's also not a general model for all subject-object rights.

Concept tested. Access control models - Access matrix

Reference. https://csrc.nist.gov/glossary/term/access-matrix

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