Continuing the Chrome extension hacking (see part 1 and 2), this time I’d like to draw you attention to the oh-so-popular AdBlock extension. It has over a million users, is being actively maintained and is a piece of a great software (heck, even I use it!). However - due to how Chrome extensions work in general it is still relatively easy to bypass it and display some ads. Let me describe two distinct vulnerabilities I’ve discovered. They are both exploitable in the newest 2.5.22 version.