Good Code, Bad Computations: A Computer Security Gray Area

ScienceDaily (2008-11-03) -- If you want to make sure your computer or server is not tricked into undertaking malicious or undesirable behavior, it's not enough to keep bad code out of the system. New research shows that the process of building bad programs from good code using "return-oriented programming" can be automated and that this vulnerability applies to multiple computer architectures. [more]

Basically, a hacker hacks a website for example and rewrites some of the existing code instead of injecting his own outside code on the website to do some potentially malicious behavior. Good job for the researchers for imagining the unimaginable.