PicoCTF Writeup – Glitch Cat
# Information:
CTF Name: PicoCTF
CTF Challenge: Glitch Cat
Challenge Category: General Skills
Challenge Points: 100
Beginner picoMini 2022.
# Challenge Description:
Our flag printing service has started glitching!
$ nc saturn.picoctf.net 65353
Hints:
# Writeup:
Hello, and welcome to another picoCTF challenge write-up. This challenge is interesting to help us learn how to write a small python script.
Step 1:
First, I ran the command:
$ nc saturn.picoctf.net 65353Below you have the output:
From experience, I know that 0x39 represents an hexadecimal character. And also, the chr function is Python 3 syntax. This function, simply “Return the string representing a character whose Unicode code point is the integer i” (soruce). In our case, we have 0x before the integer (indicating hexadecimal), therefore, it will convert from hexadecimal representation into the respective ASCII character. Example:
0x39 = ‘9’
0x63 = ‘c’
…
Therefore, to solve this challenge we have to create a simple Python 3 script (or simply use the Python 3 console):
1
2
flag_missing_part = chr(0x39) + chr(0x63) + chr(0x34) + chr(0x32) + chr(0x61) + chr(0x34) + chr(0x35) + chr(0x64)
print("picoCTF{gl17ch_m3_n07_" + flag_missing_part + "}")
To better understand the conversion, you can also try to do this manually by using an ASCII table.
But I am lazy, so I will use the script:
I got the flag.
The flag is:
Thank you very much for reading!
Cheers,
MRegra
