Match each security model to its primary characteristic.
Drag a concept onto its matching description — or click a concept then click the description.
No read up, no write down
No read down, no write up
Well-formed transactions and separation of duties
Prevents conflict of interest among clients
Rules for granting and taking permissions
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
Bell-LaPadula: Enforces confidentiality by preventing read up and write down
The correct matches are: Bell-LaPadula (confidentiality, no read up/no write down), Biba (integrity, no read down/no write up), Clark-Wilson (integrity, well-formed transactions and separation of duties), and Brewer-Nash (confidentiality, conflict of interest). Common confusions involve swapping the rules between Bell-LaPadula and Biba.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
Bell-LaPadula: Enforces confidentiality by preventing read up and write down
Why this is correct
The Bell-LaPadula security model is fundamentally designed to enforce confidentiality, preventing unauthorized disclosure of information. It achieves this through two primary rules: the Simple Security Property, which prohibits a subject from reading information at a higher security level ('no read up'), and the *-Property (star property), which prevents a subject from writing information to a lower security level ('no write down'). These rules ensure that information flows only from lower to higher security levels, maintaining strict secrecy.
Biba: Enforces integrity by preventing read down and write up
Why this is correct
The Biba integrity model is specifically engineered to maintain data integrity, protecting against unauthorized modification or corruption. Its core principles are the Simple Integrity Property, which prevents a subject from reading data at a lower integrity level ('no read down'), and the *-Integrity Property, which prohibits a subject from writing to a higher integrity level ('no write up'). These rules ensure that high-integrity data is not contaminated by less trusted sources, preserving its accuracy and trustworthiness.
Clark-Wilson: Enforces integrity through well-formed transactions and separation of duties
Why this is correct
The Clark-Wilson model is an integrity model focused on commercial and transactional systems, emphasizing well-formed transactions and separation of duties. It ensures integrity by requiring that data modifications occur only through certified Transformation Procedures (TPs) acting on Constrained Data Items (CDIs). Furthermore, it mandates separation of duties, preventing a single individual from performing all steps necessary to complete a critical transaction, thereby mitigating fraud and error.
Brewer-Nash: Enforces confidentiality to prevent conflicts of interest
Why this is correct
The Brewer-Nash model, also known as the Chinese Wall model, is a confidentiality model designed to prevent conflicts of interest, particularly in industries like finance. It dynamically restricts access to information based on a subject's prior access history. Once a subject accesses information related to one company within a conflict-of-interest dataset, they are subsequently prevented from accessing information related to competing companies in that same dataset, thus maintaining impartiality.
Bell-LaPadula: Enforces integrity by preventing read down and write up
Why it's wrong here
This statement incorrectly attributes the rules of the Biba integrity model to Bell-LaPadula. Bell-LaPadula is exclusively a confidentiality model, focusing on preventing information disclosure, not integrity. Its rules are 'no read up' and 'no write down,' which are the inverse of those stated here, highlighting a fundamental misunderstanding of its purpose and mechanisms.
Biba: Enforces confidentiality by preventing read up and write down
Why it's wrong here
This option incorrectly describes the Biba model as enforcing confidentiality with rules belonging to Bell-LaPadula. Biba is an integrity model, specifically designed to prevent unauthorized modification or corruption of data. The rules 'no read up' and 'no write down' are characteristic of Bell-LaPadula, which prioritizes secrecy, making this description fundamentally inaccurate for Biba.
Go deeper
Learn chapter
Security Governance and Principles
Key term
Security model
A security model is a formal framework that defines how subjects (users, processes) can access objects (files, resources) based on rules, ensuring confidentiality, integrity, and availability.
Key term
Security
Security in IT is the practice of protecting systems, networks, and data from unauthorized access, damage, or theft.
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