Beep64
Challenge Description
Every CTF needs a base64 challenge... right?
Attachments
Solution
Unzip the file, we get a wav file which is 37 mins long
Listening to the audio file, it is DTMF tones
Online decoders dont work for such a long audio file
Using this repo we can decode the audio file
DTMF Output: out.txt
Removing the
*
and replacing withspaces
Decoding the rest using T9 Decoder
Replace
SPACE
: nothingZERO
: 0ONE
: 1
Decode using Binary and then Base64 decoding gives us the flag
FLAG
Resources
DTMF Decoder: https://github.com/ribt/dtmf-decoder
T9 Decoder: https://www.cachesleuth.com/vanity.html
Cyberchef: https://gchq.github.io/CyberChef/
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