Tornado Warning [UIUCTF 2023]

writeup by: zenbassi

Challenge Description

Check out this alert that I received on a weather radio. Somebody transmitted a secret message via errors in the header! Fortunately, my radio corrected the errors and recovered the original data. But can you find out what the secret message says?

Note: flag is not case sensitive.
Author: Pomona

The header is encoded with Specific Area Message Encoding.

The three buzzes are supposed to be identical, but in this challenge, they are different due to errors.


Even without the hints, it’s pretty easy to find out about SAME. As it usually goes with this challenges, all that’s left to do is find a tool that can interpret the given .wav file.


We found this thread from 2013 talking precisely about what we’re interested in. Using seatty with the same setting, we got 3 messages. For each position there were two ASCII options to chose from. One of them appeared once and the other twice. By choosing the characters that appeared once, we obtained the flag.