📌 Challenge Summary

You’re placed at 10.0.0.1 and must connect to a remote server at 10.0.0.2 on port 31337.

This challenge tests basic understanding of TCP client connections. The server simply listens and sends back a flag upon connection.

🧠 Understanding the Setup

The provided Python code inside /challenge/run:

import socket

class ServerHost(Host):
    def entrypoint(self):
        server_socket = socket.socket()
        server_socket.bind(("0.0.0.0", 31337))
        server_socket.listen()
        while True:
            try:
                connection, _ = server_socket.accept()
                connection.sendall(flag.encode())
                connection.close()
            except ConnectionError:
                continue
  • The server binds to 0.0.0.0:31337.
  • When a client connects, it sends the flag and closes the connection.

How We Exploit It

There is no exploit needed — just use Netcat (nc) to connect.

nc 10.0.0.2 31337

Final Exploit Command

root@ip-10-0-0-1:~# nc 10.0.0.2 31337
pwn.college{gg1HJhGCkcntOmNvNCXZK6pp_wK.QX5UzMzwSM0IzMyEzW}

Output

pwn.college{gg1HJhGCkcntOmNvNCXZK6pp_wK.QX5UzMzwSM0IzMyEzW}

Flag

pwn.college{gg1HJhGCkcntOmNvNCXZK6pp_wK.QX5UzMzwSM0IzMyEzW}