Hack the code! (350)
reversing - Louisa County High School
Challenge description:
Download the attached checkkey.exe. Run it on a windows computer. Your task it to reverse engineer this program to break the code. Once you break the code, enter the flag to win the game!
The flag format is CTF{key}
Solution
Before I ran it on Windows, I decided to run a strings command just to be safe.
$ strings hackthecode.exe -n 10
!This program cannot be run in DOS mode.
<ItC<Lt3<Tt#<h
<ItC<Lt3<Tt#<h
PP9E u:PPVWP
the item you seek is encrypted nearby
596F7544696449543335305074733255
...
Decoding the hex returns:
$ echo "596F7544696449543335305074733255" | xxd -r -p
*****************%