Maximum Sound
Dang, this track really hits the target! It sure does get loud though, headphone users be warned!!
At first, I tried the typical audio steg solves: mostly LSB and spectrogram analysis. Having no luck, and noticing how “robotic” the audio sounds, I figured it was a matter of decoding the audio (sort of like morse, but obviously not morse in this scenario). It honestly took me a bit to analyze different signals, but eventually, I remembered SSTV. Listening to an SSTV sample and comparing it to ours— it is an instant match. We can use sstv -d maximum_sound.wav -o result.png to decode it, and we get what looks like a QR code. However, it’s not a QR code and most decoders will fail. That’s because it’s MaxiCode (now, hence the name Maximum sound?). If we crop the image to just the QR code, we can then use zxing (https://zxing.org/w/decode.jspx) to decode the MaxiCode and get the flag: flag{d60ea9faec46c2de1c72533ae3ad11d7}