AppSec California 2020

Nowadays, JSON Web Tokens are everywhere. They are used as session tokens or just to pass data between applications or µservices. By design, JWT contains a high number of security and cryptography pitfalls. In this talk, we are going to learn how to exploit (with demos) some of those issues. After covering the basics (None and Algorithm confusion), we are going to move to kid injection, embedded JWK (CVE-2018-0114). Finally, we will look at jku and x5u attributes and how they can be abused by chaining vulnerabilities.