CyberGlossary

Identity & Access

Attribute-Based Access Control (ABAC)

Also known as: ABAC, Policy-based access control

Definition

An authorization model that evaluates policies over attributes of the subject, resource, action, and environment to decide whether to allow an access request.

Attribute-Based Access Control replaces static role assignments with dynamic policies. A decision engine evaluates rules over attributes such as the user's department and clearance, the resource's classification, the requested action, the time of day, and the device posture. This enables very fine-grained, context-aware decisions — for example, allowing a doctor to read a chart only during their on-call shift and from a managed device. ABAC is described in NIST SP 800-162 and implemented through standards like XACML and OPA Rego. Its strengths are flexibility and scale; its weaknesses are policy complexity, harder auditing, and the need for trustworthy attribute sources.

Examples

  • An OPA policy allowing access only if user.region == resource.region and device.compliant == true.
  • A XACML rule restricting export of personal data to EU users from EU IP ranges.

Related terms