From owner-freebsd-security@FreeBSD.ORG Wed Apr 21 04:51:47 2004 Return-Path: Delivered-To: freebsd-security@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 3A2AC16A4CE for ; Wed, 21 Apr 2004 04:51:47 -0700 (PDT) Received: from gw.celabo.org (gw.celabo.org [208.42.49.153]) by mx1.FreeBSD.org (Postfix) with ESMTP id EC73B43D2D for ; Wed, 21 Apr 2004 04:51:46 -0700 (PDT) (envelope-from nectar@celabo.org) Received: from localhost (localhost [127.0.0.1]) by gw.celabo.org (Postfix) with ESMTP id 7325B5489C; Wed, 21 Apr 2004 06:51:46 -0500 (CDT) Received: from gw.celabo.org ([127.0.0.1]) by localhost (hellblazer.celabo.org [127.0.0.1]) (amavisd-new, port 10024) with SMTP id 84139-03; Wed, 21 Apr 2004 06:51:35 -0500 (CDT) Received: from lum.celabo.org (lum.celabo.org [10.0.1.107]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client CN "lum.celabo.org", Issuer "celabo.org CA" (verified OK)) by gw.celabo.org (Postfix) with ESMTP id 922815486E; Wed, 21 Apr 2004 06:51:24 -0500 (CDT) Received: by lum.celabo.org (Postfix, from userid 501) id 7CDDE1D0CF9; Wed, 21 Apr 2004 06:47:20 -0500 (CDT) Date: Wed, 21 Apr 2004 06:47:20 -0500 From: "Jacques A. Vidrine" To: Dag-Erling =?iso-8859-1?Q?Sm=F8rgrav?= Message-ID: <20040421114720.GD19738@lum.celabo.org> Mail-Followup-To: "Jacques A. Vidrine" , Dag-Erling =?iso-8859-1?Q?Sm=F8rgrav?= , Mike Tancsa , freebsd-security@freebsd.org References: <6.0.3.0.0.20040420125557.06b10d48@209.112.4.2> Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline In-Reply-To: X-Url: http://www.celabo.org/ User-Agent: Mutt/1.5.6i Content-Transfer-Encoding: quoted-printable cc: freebsd-security@freebsd.org Subject: Re: TCP RST attack X-BeenThere: freebsd-security@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list List-Id: Security issues [members-only posting] List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 21 Apr 2004 11:51:47 -0000 On Tue, Apr 20, 2004 at 07:44:37PM +0200, Dag-Erling Sm=F8rgrav wrote: > Mike Tancsa writes: > > http://www.uniras.gov.uk/vuls/2004/236929/index.htm >=20 > The advisory grossly exaggerates the impact and severity of this > fea^H^H^Hbug. The attack is only practical if you already know the > details of the TCP connection you are trying to attack, or are in a > position to sniff it. =20 Well, the whole point is that *although in the past it was widely believed otherwise*, this attack is practical today in some real world situations. It many cases the only unknown is the source port number, and even that can be predictable. [...] > I don't believe BGP sessions are as exposed as the advisory claims > they are, either. The possibility of insertion attacks (which are > quite hard) was predicted six years ago, when RFC 2385 (Protection of > BGP Sessions via the TCP MD5 Signature Option) was written. RST > attacks may cause route flapping, but that can be avoided with a short > hysteresis (though this may be impractical for backbone routers) If the DoS attack causes route flapping, then the attack is a success. > Insertion attacks against SSL connections are practically impossible, > so the only risk there is an RST attack, which most browsers should > handle gracefully. >=20 > DNS connections (even zone transfers) are so short-lived that you > would have to be very, very lucky to pull off an insertion or RST > attack against. Yes, these seem to be stretches. > The most likely attack scenario to come out of this is probably gamers > and IRC weenies kicking eachother off servers (the server's IP address > and port number are known, the servers often reveal client IP > addresses to other clients, and the client often uses a fixed source > port, or one from a relatively small range) Every time someone is kicked off an IRC server (or otherwise restrained from online chat), global productivity rises :-) Cheers, --=20 Jacques Vidrine / nectar@celabo.org / jvidrine@verio.net / nectar@freebsd= .org