Dethstarr was one of my favorite service exploitation challenges during the SecuInside 2012 contest. We had to fully reverse a given binary to understand how the protocol it implements works. To be able to debug the binary easily and in the same environment as on the remote server...

Original writeup (http://blog.lse.epita.fr/articles/19-secuinside2k12-prequals-dethstarr-writeup.html).