Course

This course explains the exploitation of an insecure OAuth2 Client that is susceptible to Cross-Site Request Forgery (CSRF) because it does not utilize the state parameter in the OAuth2 flow. The OAuth2 Client uses OAuth2 as a pseudo-authentication mechanism, and this vulnerability allows an attacker to link the victim's account on the OAuth2 Client to an account controlled by the attacker.

To exploit this vulnerability, you need to register a malicious account on the Authorization Server and initiate the OAuth2 process on the OAuth2 Client. By intercepting and manipulating the request that redirects the User-Agent to the OAuth2 Client, you can perform a CSRF attack to link the victim's account with your malicious account. This grants you access to the victim's information on the OAuth2 Client website, demonstrating the critical importance of proper OAuth2 implementation.