OAuth2: Authorization Server OpenRedirect

This course provides a detailed walkthrough of how to exploit vulnerabilities in an OAuth2 Authorization Server. OAuth2 is a protocol designed to grant access to resources to a client, involving four main parties: the Resource Owner, the OAuth2 Client, the Authorization Server, and the Resource Server. The course covers the typical OAuth2 flow, where the Resource Owner authorizes the OAuth2 Client to access resources via the Authorization Server, and also delves into inspecting HTTP traffic to understand the interactions better.

A significant part of the course focuses on a common OAuth2 vulnerability where the Authorization Server does not enforce the redirect URL. This flaw can be exploited by attackers to intercept the OAuth2 code by tricking the victim into visiting a malicious link. The attacker can then use this code to gain unauthorized access to the victim's resources. The course concludes by emphasizing the importance of identifying and fixing such vulnerabilities to secure OAuth2 implementations.