[69824] in North American Network Operators' Group
Re: TCP RST attack (the cause of all that MD5-o-rama)
daemon@ATHENA.MIT.EDU (Dan Hollis)
Tue Apr 20 17:23:32 2004
Date: Tue, 20 Apr 2004 14:11:02 -0700 (PDT)
From: Dan Hollis <goemon@anime.net>
To: Crist Clark <crist.clark@globalstar.com>
Cc: "Patrick W.Gilmore" <patrick@ianai.net>, <nanog@merit.edu>
In-Reply-To: <40858BCA.3090004@globalstar.com>
Errors-To: owner-nanog-outgoing@merit.edu
On Tue, 20 Apr 2004, Crist Clark wrote:
> But it has limited effectiveness for multi-hop sessions. There is the
> appeal of a solution that does not depend of the physical layout of the
> BGP peers.
Does MD5 open the door to cpu DOS attacks on routers though? Eg can
someone craft a DOS attack to take out the CPU on a router by forcing it
to MD5 authenticate torrents of junk packets, using less bandwidth than
it would take to DOS the links themselves?
As has been pointed out, blind attacker needs to guess the source port as
well, which would seem to multiply the search space blind attackers need
to hit (the tcpsecure paper states as much - "assuming the attacker can
accurately guess both ports")
Are such attacks still practical in that light?
-Dan
