JWT IX
This exercise covers how to use the jku header to bypass an authentication based on JWT.
In this exercise, we delve into the jku header in JWT tokens, focusing on how to forge a token to gain admin privileges. The jku header allows users to link to a public key within the token's header. However, if the application trusts this URL without verification, an attacker can provide their own URL and sign the message using a corresponding private key.
You will learn to create a private and public key, build a JWK file, and upload it to the server to bypass URL restrictions. By understanding this process, you'll see how attackers can manipulate JWT tokens even when the payload is signed, highlighting potential vulnerabilities in signature mechanisms.