CrossCTF_2017: Sky Pillar 4

Category: Reverse Engineering Points: 300 Description:

192.168.0.31:1350 Please start from level 01

Write-up

This one was the pinnacle of my reverse engineering skill. With a little luck, you would guess that this is related to Fibonacci numbers, unfortunately, I did not in time for competition, so I just transpiled everything into solve.c.

$ gcc solve.c && ./a.out 
Currently on 584
Found! 584
$ ./skypillar
                                 Welcome to                                    
 ______     __  __     __  __        ______   __     __         __         ______     ______
/\  ___\   /\ \/ /    /\ \_\ \      /\  == \ /\ \   /\ \       /\ \       /\  __ \   /\  == \
\ \___  \  \ \  _"-.  \ \____ \     \ \  _-/ \ \ \  \ \ \____  \ \ \____  \ \  __ \  \ \  __<
 \/\_____\  \ \_\ \_\  \/\_____\     \ \_\    \ \_\  \ \_____\  \ \_____\  \ \_\ \_\  \ \_\ \_\
  \/_____/   \/_/\/_/   \/_____/      \/_/     \/_/   \/_____/   \/_____/   \/_/\/_/   \/_/ /_/
================================================================================
                    Home of the legendary Pokemon, Rayquaza                          
================================================================================
There are 5 Levels to climb. Each level requires a specifc code to unlock the next level.
Your goal is to reach the top, and catch the legendary Rayquaza... Good luck!
====================================================================
                          LEVEL 01                                  
====================================================================
Enter code: I w@nn@ be the very best
CrossCTF{xxxxxxxxxxxxxxxxx}
====================================================================
                          LEVEL 03                                  
====================================================================
Enter Code: 0 @ C D G
CrossCTF{xxxxxxxxxxxxxxxxx}
====================================================================
                          LEVEL 04                                  
====================================================================
Enter Code: 584
CrossCTF{xxxxxxxxxxxxxxxxx}

Therefore, the flag is ``.