CISSP Security Architecture and Engineering Practice Question
A financial institution must ensure that transactions are well-formed and enforce separation of duties to prevent fraud. Which security model best addresses these requirements?
⚠ Common exam trap
CISSP often tests the confusion between integrity models (Biba, Clark-Wilson) and confidentiality models (Bell-LaPadula), and between Clark-Wilson's commercial integrity focus and Biba's hierarchical integrity levels.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Clark-Wilson
The Clark-Wilson model is specifically designed for commercial integrity and enforces well-formed transactions and separation of duties through its access control triple (subject, program, object). It ensures that data can only be modified through certified transformation procedures, which directly addresses the requirement for well-formed transactions and fraud prevention via separation of duties. This makes it the correct model for financial transaction integrity.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Biba
Why it's wrong here
The Biba integrity model primarily focuses on preventing subjects from writing to objects at a lower integrity level (no write down) and reading from objects at a higher integrity level (no read up). While effective for maintaining data integrity levels and preventing unauthorized data corruption, it does not inherently define mechanisms for validating the structure or business logic of financial transactions. Consequently, Biba does not explicitly address the requirements for well-formed transactions or the enforcement of separation of duties within application processes.
- ✓
Clark-Wilson
Why this is correct
The Clark-Wilson integrity model is specifically designed for commercial environments requiring strong data integrity, well-formed transactions, and accountability. It enforces integrity through constrained data items (CDIs) that can only be modified by certified transformation procedures (TPs), which are executed by authorized users under strict separation of duties. This model directly addresses the need for controlled, validated operations and accountability in financial systems, ensuring transactions are processed correctly and preventing fraud.
- ✗
Brewer-Nash
Why it's wrong here
The Brewer-Nash model, also known as the Chinese Wall policy, is designed to prevent conflicts of interest by restricting a subject's access to information based on their prior access history. Once a subject accesses data related to one company within a conflict-of-interest class, they are prevented from accessing data related to competing companies in that same class. This model does not, however, provide mechanisms for ensuring the internal consistency, validity, or proper execution of financial transactions themselves.
- ✗
Bell-LaPadula
Why it's wrong here
The Bell-LaPadula model is a foundational security model primarily focused on enforcing confidentiality in multi-level security systems. It prevents unauthorized information flow from higher security levels to lower ones through its 'no read up' (Simple Security Property) and 'no write down' (*-property) rules. While crucial for protecting classified data, this model does not inherently address the integrity of transactions or the proper execution of business processes, which are central to ensuring well-formed financial operations.
Go deeper
Related to this question
Learn chapter
Access Control Models and Mechanisms
Key term
Clark-Wilson
A security model that enforces data integrity by ensuring that only authorized, well-formed transactions change data, and that those changes are logged and controlled.
Key term
Access control
Access control is the security practice of determining who or what is allowed to view, use, or enter a resource, and under what conditions.
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JA
Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed September 2026 · checked against the official ISC2 exam blueprint
This CISSP practice question is part of Courseiva's free ISC2 certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the CISSP exam.