Recently, I played in the DefCon CTF quals and there I saw a very interesting challenge called Mute [1]. It was a exploiting challenge, the flow control was very easy but the real challenge was in the libseccomp [2] bypass. It is a library to forbid syscalls that You don't want that the program executes. So, the write syscall wasn't allow. I had not success with this challenge, but These are to learn!!! So, later, I read the writeup and …