I recently participated in the NahamCon CTF with the team Hacking for Soju. I was unable to complete this challenge before the end of the CTF, but managed to solve it the following day. Credits to maneolt and xehle for sharing notes and giving me a couple nudges.
Shout-out to the challenge creator Adam Langley (give him a follow) for keeping the hype going after the CTF ended and also making one of the better web CTFs I have seen!
It starts with Hackbookagram.com