The Challenge

The server expects a specific format for the echoed response. The raw server output is a word. The protocol demands it be wrapped: a leading ?, the content uppercased, and a trailing !. Sending the word back through the right formatter earns the flag.

Approach

Receive the server’s prompt, strip the newline, uppercase the content, prepend ? and append !. The server validates the format and returns the flag on the next line — trimmed to skip the first 34 characters (a fixed-length preamble before the actual flag value).

Solution

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#!/usr/bin/env python3
from pwn import *

r = remote("wordwang.challs.olicyber.it", 10601)
r.recvline()
x = b'?' + r.recvline().replace(b'\n', b'').upper() + b'!'; print(x)
r.sendline(x)
print("\n\n"+ r.recvline()[34:].decode() + "\n\n")

r.recvline() discards the server’s greeting. The second recvline() receives the word. Stripping \n, uppercasing, prepending ? and appending ! builds the protocol-correct response in one expression. r.recvline()[34:] skips the fixed preamble text and prints the flag.

What I Learned

Custom-protocol challenges often require nothing more than reading the spec carefully and implementing the formatting rule. Pwntools remote with recvline / sendline is the fastest way to prototype a protocol client — the only real work is understanding what format the server expects back.