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ISC2 CC Practice Question: A government agency uses a multi-level security…
A government agency uses a multi-level security system with mandatory access control (MAC). A user with Secret clearance attempts to write data to a file classified as Confidential. Under the Bell-LaPadula model, which rule applies and what is the outcome?
⚠ Common exam trap
ISC2 often tests the confusion between the simple security property (no read up) and the *-property (no write down), leading candidates to mistakenly apply the read rule to a write operation or assume that higher clearance allows writing down.
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
✓
The *-property (no write down) denies the operation
The Bell-LaPadula model enforces mandatory access control (MAC) with two primary rules: the simple security property (no read up) and the *-property (no write down). In this scenario, a user with Secret clearance attempts to write to a Confidential file, which is a write-down operation. The *-property prohibits writing to a lower classification to prevent the leakage of higher-classified information, so the operation is denied. Option D correctly identifies this rule and outcome.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
The simple security property (no read up) denies the operation
Why it's wrong here
The user is writing, not reading; this property applies to reading.
- ✗
The *-property allows the operation because the user is writing down
Why it's wrong here
Writing down is prohibited by the *-property to prevent downgrading.
- ✗
The simple security property allows the operation because the user's clearance is higher
Why it's wrong here
Simple security applies to reading, not writing, and would allow reading down, not writing down.
- ✓
The *-property (no write down) denies the operation
Why this is correct
The Bell-LaPadula model's \*-property (star property) specifically enforces "no write down", a critical rule for maintaining confidentiality. This property dictates that a subject cannot write to an object with a lower security classification. Here, the user with Secret clearance attempts to write to a Confidential file. As Secret is a higher classification than Confidential, this operation is a write-down, which the \*-property consequently denies to prevent information flow to lower levels.
Quick reference
Access Control Model Comparison
| Model | Acronym | Who Controls Access? | Best For |
|---|---|---|---|
| Discretionary Access Control | DAC | Resource owner | Small teams, file shares |
| Mandatory Access Control | MAC | System / security labels | Classified govt / military |
| Role-Based Access Control | RBAC | Administrator (via roles) | Enterprise environments |
| Attribute-Based Access Control | ABAC | Policy engine (user + resource attributes) | Fine-grained, dynamic policies |
| Rule-Based Access Control | RuBAC | System rules / ACLs | Firewall rules, network ACLs |
Go deeper
Related to this question
Learn chapter
Introduction to Security Principles
Key term
Least privilege
Least privilege is a security principle that means giving users, systems, or programs only the minimum permissions they need to do their job and nothing more.
Key term
Bell-LaPadula
A formal security model that prevents users from reading information at a higher classification level than their own and from writing information down to a lower classification level.
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This CC 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 CC exam.