DEF CON 29 - Barak Sternberg - Extension Land Exploits and Rootkits in  Browser Extensions - LIVE
Channel: DEFCONConference
Date: 2021-08-30

Browser extensions are installed anywhere, they serve as an integral part of our day-to-day web routine, from AdBlockers to Auto-Translators. But - do we know what is running inside of them? Do we know what goes deep-down inside their communication routines? How do they use their internal API’s? And how do their different JS execution contexts work?

In this session, I will explore these unique internal extension API’s, hidden attack-surfaces and show how these concepts can be broken & exploited using new ways! I start showing how an attacker can "jump" from one low-permissions chrome-app/extension to another, hence elevating its permissions. Then, I will show how to gain full "browser-persistency" inside extensions' background-scripts context.

Chaining it all together, I show how attacker, starting from low permissions chrome-app, gains a fully-armed "extension-rootkit", a persistent JS-malware running inside of a “good” extension, along with C&C features, JS injection techniques to any tab/origin, obfuscation-techniques and more. Eventually, I will present a generic technique, targeting all chrome-users, for taking over any previously installed chrome extension and implant an "extension-rootkit" in it.