What does the hierarchy of privileges reference in access control?

The hierarchy of privileges in access control refers to the order in which permissions are evaluated and applied. Understanding this hierarchy is essential for effectively managing user access rights within information systems.

In this context, the correct answer outlines a common approach known as the "Deny by default" principle. This principle asserts that if a user or object is not explicitly granted permission to access a resource, the default action is to deny access. Therefore, the explicit deny takes precedence over any permissive settings. Following the explicit deny is the explicit permit, which grants access when a user's permissions allow it. If neither an explicit permit nor an explicit deny is defined, then the system defaults to an implicit deny, meaning access is denied.

This prioritization is critical for ensuring security in access control systems, as it prevents unintended permissions from being granted and helps to minimize the attack surface by ensuring that only those who need access receive it, based on explicit permissions set by administrators.

Understanding this hierarchy allows security professionals to design and maintain access control mechanisms in a way that protects sensitive information while allowing necessary access based on established policies.