Lab: Stealing OAuth access tokens via a proxy page
Summary: PortSwigger's lab demonstrates an OAuth service whose flawed validation lets an attacker leak access tokens to arbitrary pages on the client application. The exercise requires finding a secondary vulnerability in the client application, using it as a proxy to steal the admin user's access token, and then using that token to obtain the admin's API key.
What's compelling: The admin account in the lab opens anything sent from the exploit server and always holds an active OAuth session, so a single redirect_uri manipulation via directory traversal is enough to hand over a token that unlocks the admin's API key.
Read the original at PortSwigger Research ↗
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