Dailydave mailing list archives
Re: DNS Speculation
From: Jon Oberheide <jon () oberheide org>
Date: Mon, 21 Jul 2008 14:54:59 -0400
Halvar, On Mon, 2008-07-21 at 10:24 +0200, Halvar Flake wrote: [snip]
Mallory wants to poison DNS lookups on server ns.polya.com for the domain www.gmx.net. The nameserver for gmx.net is ns.gmx.net. Mallory's IP is 244.244.244.244. Mallory begins to send bogus requests for www.ulam00001.com, www.ulam00002.com ... to ns.polya.com. ns.polya.com doesn't have these requests cached, so it asks a root server "where can I find the .com NS?" It then receives a referral to the .com NS. It asks the nameserver for .com where to find the nameserver for ulam00001.com, ulam00002.com etc. Mallory spoofs referrals claiming to come from the .com nameserver to ns.polya.com. In these referrals, it says that the nameserver responsible for ulamYYYYY.com is a server called ns.gmx.net and that this server is located at 244.244.244.244. Also, the time to live of this referral is ... long ... Now eventually, Mallory will get one such referral spoofed right, e.g. the TXID etc. will be guessed properly. ns.polya.com will then cache that ns.gmx.net can be found at ... 244.244.244.244. Yay.
This step is the difficult part where the scenario breaks down. When the attacker is asking the resolver to service the bogus requests, the resolver will query the .com authoritative server (question section RR: ulamYYYYY.com/A/IN). Since each query the resolver sends has a different transaction ID, you're still be stuck having to guess the 16-bit TXID. And since each query has a different question section, the bday attack scenario is not possible. Regards, Jon Oberheide -- Jon Oberheide <jon () oberheide org> GnuPG Key: 1024D/F47C17FE Fingerprint: B716 DA66 8173 6EDD 28F6 F184 5842 1C89 F47C 17FE
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Current thread:
- DNS Speculation Halvar Flake (Jul 21)
- Re: DNS Speculation Jon Oberheide (Jul 21)
- Re: DNS Speculation Petja van der Lek (Jul 21)
- Re: DNS Speculation natron (Jul 22)
- Re: DNS Speculation Parity (Jul 22)
- Re: DNS Speculation Tetrapodal Giant (Jul 22)
- Re: DNS Speculation Blue Boar (Jul 23)
- Re: DNS Speculation Alexander Sotirov (Jul 22)
- Re: DNS Speculation natron (Jul 22)
- Re: DNS Speculation Dominique Brezinski (Jul 22)
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- Re: DNS Speculation Dominique Brezinski (Jul 22)
- Re: DNS Speculation Petja van der Lek (Jul 22)