Glitch Cat

Tags: General Skills, nc, shell, Python
Author: LT ‘syreal’ Jones

Description

Our flag printing service has started glitching!
$ nc saturn.picoctf.net 50562

Hints

1. ASCII is one of the most common encodings used in programming
2. We know that the glitch output is valid Python, somehow!
3. Press Ctrl and c on your keyboard to close your connection and return to the command prompt.

   Approach

   If we open Terminal and connect with nc saturn.picoctf.net 50562 (input that line) then we get an output:

   'picoCTF{gl17ch_m3_n07_' + chr(0x38) + chr(0x39) + chr(0x38) + chr(0x61) + chr(0x33) + chr(0x66) + chr(0x61) + chr(0x36) + '}'
   

   In Python, chr is a command that turns numbers into characters. ASCII is a type of number to character and character to number encoding. If we run

   print('picoCTF{gl17ch_m3_n07_' + chr(0x38) + chr(0x39) + chr(0x38) + chr(0x61) + chr(0x33) + chr(0x66) + chr(0x61) + chr(0x36) + '}')
   

   in the Python shell or as a new Python file and it should output the flag.

   Flag

   picoCTF{gl17ch_m3_n07_898a3fa6}