This is a cracking and keygen tutorial by the reader qwertyoruiop. He’s having fun doing the crackmes and I asked him to write tutorials about them and he did it! So here it is the first in full glory. Things been quiet around here but busy in real life. I wanted to write a few posts about OS X malware but I’m going to present at a conference in July on that topic (hopefully something interesting!...
I have a passion for the Human brain and Human behavior and I love to experiment with anything. My birthday is near so it’s a good time to go forward with this idea. The starting point is that this blog is absolutely non-profit oriented and that status will remain forever – no banners, no donations, etc. I do it purely for fun, pleasure and knowledge improvement, altough it generates positive externalities (aka work!...
One obstacle that I faced long time ago and came again into spotlight is how to recompile GDB for iOS. It is not useful to fix the ARM disassembler and then not be able to compile. As far as I know there isn’t any documentation available or an easy method to accomplish this – Saurik’s build environment is not public (?) and Apple sources do not compile directly. Darwinbuild project works great for OS X but it’s a question mark for iOS....
Here it is, a merge between the x86 and ARM versions of gdbinit. The only inconvenience is that you need to manually change the target, using the 32bits and 64bits commands for x86/x86_64 architectures, and arm for ARM. That’s a small price to pay for. This version features a lot of cosmetic fixes (indentation mostly) but also some fixes to the ARM related code, and a new command – dumpmacho. This command will dump the Mach-O header to a file....
The title of this post is a partial rip-off of Dynamic Code Encryption as an Anti Dump and Anti Reverse Engineering measure blogpost. Alexey describes a technique similar to the one I used in my crackme, which isn’t altogether that new. His post is a good introduction to some possible attack vectors and what is at stake. You should give it a look. The crackme uses a multi-layer dynamic code encryption approach, with two different encryption algorithms (Rabbit and Salsa)....