Destructive Voice

a CTF team from Ural Federal University, Yekaterinburg

DEFKTHON 2014 Misc 300

Try to extract downloaded 73168.zip. It’s password protected, but we can see that there is only 46783.zip file inside. So try password 46783.

It’s successfuly unpacked. Try to do the same with 46783.zip. Now we have the next one - 47096.zip. Unpacking by hands seems too hard so write the python script:

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#!/usr/bin/env python2
# -*- coding: utf-8 -*-

import zipfile

sFile = '42819.zip'
while True:
  tz = zipfile.ZipFile(sFile).namelist()
  if (len(tz) > 1):
  print '[!]{0} contains more then one file!'.format(sFile)
  if tz[0][-4:] == '.zip':
  tzip = zipfile.ZipFile(sFile, "r")
  tzip.setpassword(tz[0][:-4])
  tzip.extractall()
  tzip.close()
  print '[+]{0} was unpacked successfuly.'.format(sFile)
  sFile = tz[0]
  else:
  print '[!]Finished.'

Wait about 40 minutes. Than we have 1.510 archives and there is mess.wav file in the last one. Brute password for this archive (it is “b0yzz”).

Try to listen mess.wav, undestand that we can hear nothing. Try to vi this file, nothing interesting again. Let’s now try to see it’s spectogram. We can now see the key here - “BallsRealBolls”.

Author: Phil Bazun