SwampCTF Writeup: Ethereal Boy

SwampCTF was this weekend and I have to say, I enjoyed the DnD theme. I also thought they had some pretty cool challenges, such as multiple game boy reversing challenges. This was a fun one and probably the easiest challenge of the game boy group. In this challenge we are given a simple game boy game ROM, containing a single room and NPC, to RE. I used bgb as the game boy emulator and booted the game up. This challenge was simple, in that you don't have to reverse it but instead can just look at the assets loaded into memory. You can view the tiles loaded into VRAM in bgb by going to Window->VRAM Viewer->Tiles. The main issue being these are unique tile assets for the flag instead of generic tiles used to build a flag dynamically. You can see the tiles, flag{und3r_th3_hood}, below: