forensics/wave

387 points

Writeup by Victor

We're given what appears to be a corrupted .wav file. Media Player practically screams this if you try opening it and playing the audio. If you try to open the file normally in Audacity (the best application for audio ctf challenges btw) it won't let you because, as hinted already, the file is corrupt. But there's one way to open corrupt files in Audacity: by importing the raw data of the file.

Importing raw data in Audacity

With the audio file successfully opened in Audacity, you should see something like this:

Visualization of the audio

I wouldn't recommend clicking the play button (speaking from experience here). But what you should notice are the lengths of each audio segment. They're all either wide or thin, no in between. This should immediately scream out to you "MORSE CODE"!

Morse code on the bottom

As drawn at the bottom of the image, the morse could is "-... . . .--. -... --- .--. -- --- .-. ... . -.-. --- -.. ." and if you input that into a morse code translator, you should get the output of "BEEPBOPMORSECODE".

Morse code translation

Flag: n00bz{beepbopmorsecode} *challenge tells you the text is in all lowercase