I'm having a reverse engineering lab at school and my last project is to beat a 10 level reverse engineering CTF-like challenge. It's got plenty of interesting things. What I need to do is find a serial key that would help me pass all 10 levels and each level is using part of the big serial key to decrypt the executable bytes for the next level and so on.

I'm currently stuck on level 7 where the executable gives me an audio wav file with weird sounds that I need to decode (there's an in-memory clue that says "Decode the message"). I initially thought it's some kind of a Morse Code but I can't figure out the breaks between letters or words. Maybe some other esoteric thing.

Here's a small sample of the audio: https://vocaroo.com/i/s0A1weOF3I3f

Does anyone have any idea what this is and how to decode it?

PS: I also ran strings, binwalk and other tools on the file but it seems to be pure audio.

PSS: Also weird thing, I guess it starts repeating the audio at some point because the exe file is 117 KB and the audio file is ~72 MB and over 5 hours long

  • This looks fun, can you share the full file? – Johann Aydinbas Jun 30 at 17:34

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