HackTheBox Crypto Challenge Call

This was the most amazing challenge to solve. I think after OSINT, I am in love with these Crypto challenges too.

For any HackTheBox Challenge you need to first look for the Files that can be downloaded or Start instances with a given port on docker.hackthebox.eu and for any zip file first password is always hackthebox.

So, I downloaded the call.zip file and unzipped it with password "hackthebox" and a "sound" mp3 file is there.

HackTheBox often consist of clues that can really help in understanding what needs to be done.

So, in this challenge we get to know that

The flag format is: HTB{PASSWORD}

I started out with this sound mp3 file and learnt that some keystrokes voice is there. So, I immediately switched to "Audacity" to analyse the voice pattern and set it on spectrogram frequencies and set it between 300 to 1800 Hz.

I noted down the number using DTMF keypad frequencies using the below table.

Now, the Number which I have induced from the table is

23 31 43 47 83 71 19 23 43 17 67 37 23 31 11 7 71 41 13.

I have noticed that these numbers are Prime Numbers and looked for the same cipher and decode it.

And pow!! I get the Flag. Now, submit it according to the Hint format.

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