> On 24 Jul 2007 17:40:35 -0000, securityfocus@xxxxxxxxxxxxxxxx > <securityfocus@xxxxxxxxxxxxxxxx> wrote: > > I don't exactly see how this is new "News" since Zalewski's paper on TCP = > sequence number analysis (which included analysis of versions of BIND): > > > > http://lcamtuf.coredump.cx/newtcp/ > > That article does not deal with attacks on BIND's PRNG. > > As far as I can tell, Joe Stewart extended Zalewski's TCP sequence > number analysis to BIND's transaction IDs - however I don't think > Stewart's paper "DNS Cache Poisoning =96 The Next Generation" ( > www.lurhq.com/dnscache.pdf ) goes as far as the recent BIND advisory > here - http://www.isc.org/sw/bind/bind-security.php: > > "The DNS query id generation is vulnerable to cryptographic analysis > which provides a 1 in 8 chance of guessing the next query id for 50% > of the query ids. This can be used to perform cache poisoning by an > attacker." > > I don't think that Amit's attack has been described before. The problem comes from ISC writing an incomplete solution to a problem initially described in 1997 (and solved, I might add). http://www.openbsd.org/advisories/res_random.txt Before 1997, the attack was even easier -- take Amit's attack and delete all the complicated math and replace it with id++. Amit just shows that ISC ignored a better solution; that of using a LCG-based generator.
