Which access control model uses fixed security labels and clearance levels to determine access?

• A. Discretionary Access Control
• B. Role-based Access Control
• C. Mandatory Access Control
• D. Attribute-Based Access Control

Answer: (C)

Access decisions are determined by fixed security labels and clearance levels, which is the hallmark of Mandatory Access Control. In this model, every subject (like a user or process) and every object (like a file or resource) carries a security label or classification. The system enforces a policy that requires the subject’s clearance to meet or exceed the object's classification, and often also considers additional compartments or categories. Because these labels are fixed and centrally managed, users cannot override permissions or grant access themselves, ensuring a non-discretionary, uniform security posture—crucial in high-security environments.

Discretionary Access Control, by contrast, lets the owner decide who can access a resource using access control lists or capabilities. Role-based Access Control assigns permissions based on a user’s role, not fixed labels. Attribute-Based Access Control makes decisions from multiple attributes of the user, resource, and context, which is more dynamic than fixed clearance levels.