The correct answer is the *-property (no write down) denies the operation. This is because the Bell-LaPadula model enforces mandatory access control with two core rules: the simple security property prevents reading up, while the star property prevents writing down to a lower classification level. In this scenario, a Secret-cleared user writing to a Confidential file constitutes a write-down, which the star property blocks to prevent the leakage of higher-classified information to a lower level. On the ISC2 Certified in Cybersecurity CC exam, this question tests your understanding of how MAC models control information flow, often appearing as a scenario where you must distinguish between read-up and write-down violations. A common trap is confusing the star property with the simple security property, so remember: the star property is about preventing high-to-low writes. For a quick memory tip, think “star stops the spill”—the star property stops sensitive data from spilling downward.
ISC2 CC Access Controls Concepts Practice Question
This CC practice question tests your understanding of access controls concepts. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
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?
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.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
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 *-property prohibits high clearances from writing to lower classifications.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
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.
Detailed technical explanation
How to think about this question
The Bell-LaPadula model is a state machine model that uses security labels (e.g., Unclassified, Confidential, Secret, Top Secret) and enforces two mandatory rules: the simple security property prevents subjects from reading objects at a higher classification, and the *-property prevents subjects from writing to objects at a lower classification. This ensures no information flows from higher to lower security levels, a concept known as 'no write down' that is critical in multi-level secure systems like those used in government or military environments. A subtle behavior is that the *-property also applies to indirect information leakage via covert channels, though the model primarily addresses direct access.
KKey Concepts to Remember
Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.
TExam Day Tips
→Watch for words such as best, first, most likely and least administrative effort.
→Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A security analyst at a medium-sized enterprise encounters this scenario during an investigation or architecture review. The correct answer reflects best practice for the specific threat or control described. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Security exam questions test whether you can match controls to threats in context — not just recall definitions.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this CC question in full detail.
Access Controls Concepts — This question tests Access Controls Concepts — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: 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.
What should I do if I get this CC question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Question Discussion
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