In my opinion, the most helpful text for transitioning from development to security would be: http://www.amazon.com/The-Software-Security-Assessment-Vulnerabil

In my opinion, the most helpful text for transitioning from development to security would be: http://www.amazon.com/The-Software-Security-Assessment-Vulnerabilities/dp/0321444426 http://www.amazon.com/The-Software-Security-Assessment-Vulne... Beyond that add in a bit of system administration knowledge e.g. in-depth knowledge of operating systems and networking, and you have everything you need to break many many systems!