Those 3 challenges were in the AI category. This is a new category in CTFs: Ph0wn created an AI challenge in 2023, and we were happy to see this category at NOPS 2024, and probably in future CTFs. Description In all 3 challenges, the goal is to manage to get the AI to tell you the flag. But, of course, the AI will do all it can not to ;)

Description This challenge has a very short description: “i heard OTP it the most secure encryption algorithm ever” and supplied a Python source file. Because that code only worked on Python 3.12, a Dockerfile was also supplied. De-obfuscating the source code The source code is intentionally obfuscated. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 import random secret = 'XXXXXXXXXXXXXXXXXXXX' PINK = 118 RED = 101 YELLOW = 97 GREEN = 108 BLACK = __builtins__ PURPLE = dir e = getattr(BLACK, bytes([RED, PINK, YELLOW, GREEN]).

Description This challenge from the Misc category was saying: “Is it me or there is a strange guy on the discord server ?” Solution Joining the Server I went on the Discord server of the CTF, and found a guy named “Joe Dohn”. I sent him a message, and immediately he replied by inviting me to a private Discord server. Actually, Joe is not real person but a bot. This private server has 2 channels: a general channel, and one dedicated to conversation with me.