Introduction We played tamuctf 2020, it was a 10 day long beginner to intermediate level ctf, 20 teams solved all the problems, we didn’t solve all the problems unfortunately and we ended in rank 25.
The reverse problems were simple/okay-ish, most of them are in rust.
The challenge This writeup is about a problem called splatter calc, it’s a rust binary that asks for an initial rng
kali@kali:/mnt/shared/ctfs/tamuctf20/rev$ ./splatter-calc Please enter an initial rng: 1 Oops, you didn't guess the right number.
Introduction BsidesSF had really really good reverse engineering challenges, but I loved two challenges. One windows reverse challenge called chameleon and another esp32 firmware reverse challenge called smart-locky which I didn’t manage to solve in time.
The challenge Problem statment We are given two files chameleon.exe and flag.png.enc, this looks trivial enough we need to reverse the encryption algorithm to give us the original flag.png.
The problem statment also says that file was encrypted in the last months.