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Sessions, SSO & Access Control · A01:2021 - Broken Access Control

Broken Access Control

Explore vertical and horizontal privilege issues, IDOR/BOLA, and server-side authorization.

Broken access control is the most common class of web application vulnerability in production today, and it sits at the top of the OWASP Top 10 as A01:2021 - Broken Access Control.

In this lesson you will:

  • Recognize a vertical privilege issue by attempting to reach the administration page as a normal customer.
  • Recognize a horizontal privilege issue and an insecure direct object reference (IDOR) — also called BOLA (Broken Object Level Authorization) in the OWASP API Security Top 10 — by examining how baskets are identified.
  • Recognize a server-side authorization failure by inspecting how the customer feedback form attributes an author to a record.

Estimated time: 10 to 15 minutes.

Prerequisite: register a normal user account in NovaCart and log in. You do not need administrative privileges for this lesson, and you should not have them.

Course position: this is the canonical authorization lesson. Later API, GraphQL, WebSocket, mass-assignment, and account-recovery lessons reuse the same rule: the server must authorize every action and object against the authenticated session.

When you are ready, send the Continue signal.