1. Web Security Academy
  2. OAuth authentication
  3. Lab

Lab: Stealing OAuth access tokens via a proxy page

EXPERT

This lab uses an OAuth service to allow users to log in with their social media account. Flawed validation by the OAuth service makes it possible for an attacker to leak access tokens to arbitrary pages on the client application.

To solve the lab, identify a secondary vulnerability in the client application and use this as a proxy to steal an access token for the admin user's account. Use the access token to obtain the admin's API key and submit the solution using the button provided in the lab banner.

The admin user will open anything you send from the exploit server and they always have an active session with the OAuth service.

You can log in with your own social media account using the following credentials: wiener:peter.