MITRE CTF 2013 – bin200 #1

We’re given an ELF binary. Opening this in IDA, the strings dump shows that this is a crackme.

IDA Strings View

Looking at the location of the invalid CD key message, it’s immediately clear where we need to end up.

IDA disasm view

We step through the program in gdb, and use set $eip =   to force the program to follow our desired jumps. Once we are where we want to be, we let the program run and are presented with our key.