DeepSec 2021 Training: How to Break and Secure Single Sign-On (OAuth and OpenID Connect) – Karsten Meyer zu Selhausen
Implementing single sign-on has huge benefits in general. It allows to design the registration and login process for users to be as simple as possible, and enables applications to be connected to social networks. Although OAuth and OpenID Connect are established as today’s common standards, serious attacks on them have been discovered within recent years. These attacks exploit the complexity of the underlying standards and implementation flaws, and allow attackers to authenticate themselves as arbitrary users or to access confidential user data. By doing so, attackers can potentially read, manipulate, or delete data of arbitrary users across these applications. Due to the critical role that single sign-on fulfills in applications nowadays, it is important to understand and address pitfalls when using OAuth and OpenID Connect. However, automatic security scanners are not able to properly