Odyssey

Description

Author: @HuskyHacks

Remember reading The Odyssey in high school? Well I sure don’t, because I never did my homework. But I really wanted to get back into the classics and give it a fair shake. The problem is I have a fourth grade reading level and that book is waaaaaay too long.

To solve this, I made a server that reads out tiny chunks of The Odyssey, one at a time, so I can take my time reading it! How is Odysseus gonna get himself out of this one?

Solution

So reading the description says it all, we have a long file to read, and we are prompted to read it section by section. Pressing ENTER will advance to the next section. As shown below:

To interact with the server and automate the process, we can use the pwn module in Python. To sum up, this script will be simulating pressing ENTER to advance to the next section of the book, and once we find the flag, it will break out of the loop and print the flag once it is found. Here is the script we called odyssey.py:

from pwn import *
import re 

conn = remote('challenge.nahamcon.com', 30617)

flag_pattern = re.compile(r'flag\{[0-9a-f]{32}\}')  

while True:
    try:
        data = conn.recvuntil(b'Press enter to continue...\n', timeout=1)  

        if data:
            print(data.decode('utf-8'))

            match = flag_pattern.search(data.decode('utf-8'))
            if match:
                print(f"Flag found: {match.group(0)}")  
                break 
)
        conn.sendline('')

    except EOFError:
        print("Server closed the connection.")
        break  

    except Exception as e:
        print(f"Error: {e}")
        break

conn.close()

Here is another version using the socket module instead of pwn module:

import socket

def solve_challenge():
    host = "challenge.nahamcon.com"
    port = 31795

    with socket.socket(socket.AF_INET, socket.SOCK_STREAM) as s:
        s.connect((host, port))

        while True:
            data = s.recv(4096).decode('utf-8')
            if not data:
                break

            print(data)

            if 'flag{' in data.lower() or 'ctf{' in data.lower():
                print("\n[+] Flag found!")
                return

            s.send(b'\n')

        print("[-] Reached end of transmission without finding flag")

if __name__ == "__main__":

Running our script using python:

> python3 odyssey.py

Flag

flag{0b51aae6b09b85d1bb13b0b8c3003a6a}