Android bootable recovery mode is a self-contained alternative boot mode that loads a tiny Linux environment onto a mobile device. While most stock devices are shipped with recoveries that are fairly limited in nature, their use can be greatly extended with a little bit of effort. In this presentation, I will show you how to build your own custom recovery for your Android device. This can be used towards a number of interesting security related goals such as: penetration testing, forensics, data acquisition, bypassing security controls, modifying software, Android development and in some cases provides a direct exploitation route into a device. Using a variety of commonly available tools, attendees will learn how to deconstruct and inspect a number of different boot and recovery software implementations and rapidly begin compiling their own custom tools and discovering vulnerabilities in their device's bootable firmware in the process.