DeadSec CTF 2024 – Mic check

This is a small write-up of the “Mic check” challenge from DeadSec CTF 2024 (Misc Category). The difficulty was easy and it was a kind of stuff that appears often in CTF challenges.

Description :

mic is it ok?
mic is it ok?

A link is to start a docker container and the command to connect to it are provided.

Solution :

When connecting to the docker with netcat, we receive a letter, we must reply with the same letter, then we receive 2 letters and must reply with the same 2 letters, and so on. We could do that manually but the “difficulty” is that you have to type the increasing amount of letters in less than 1 or 2 seconds.

A very good and easy library to use in Python to solve this challenge is called pwntools. Now we just need to make a small script that reads what we receive, and send the same string.

Then run it :

Until you see the flag :

That’s it, the flag was DEAD{mic is working!}

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