From owner-freebsd-stable Thu Jan 20 16:32:28 2000 Delivered-To: freebsd-stable@freebsd.org Received: from lariat.lariat.org (lariat.lariat.org [206.100.185.2]) by hub.freebsd.org (Postfix) with ESMTP id 8847D14C9E; Thu, 20 Jan 2000 16:32:23 -0800 (PST) (envelope-from brett@lariat.org) Received: from workhorse (IDENT:ppp0.lariat.org@lariat.lariat.org [206.100.185.2]) by lariat.lariat.org (8.9.3/8.9.3) with ESMTP id RAA11281; Thu, 20 Jan 2000 17:32:04 -0700 (MST) Message-Id: <4.2.2.20000120172607.0198f1e0@localhost> X-Sender: brett@localhost X-Mailer: QUALCOMM Windows Eudora Pro Version 4.2.2 Date: Thu, 20 Jan 2000 17:32:03 -0700 To: jamiE rishaw - master e*tard , Tom From: Brett Glass Subject: Re: bugtraq posts: stream.c - new FreeBSD exploit? Cc: Mike Tancsa , freebsd-security@FreeBSD.ORG, freebsd-stable@FreeBSD.ORG, security-officer@FreeBSD.ORG In-Reply-To: <20000120130945.B24082@x.arpa.com> References: <3.0.5.32.20000120152818.01d7fa40@staff.sentex.ca> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Sender: owner-freebsd-stable@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG At 02:09 PM 1/20/2000 , jamiE rishaw - master e*tard wrote: >I have a copy of this, which I am not giving out. I will probably >fire one off to jkh for sanity, I've been a good boy, so I hope that, er, Sanity doesn't come down the chimney of any of the systems I administer before there's a patch! ;-) >but this looks like a really tough one >to handle. > >The program basically fires off *loads* of pkts/sec of ACK at the victim >host.. random source, blah blah. > >The problem is, the kernel already (from my understanding) drops bad ACKs >pretty quickly. The thing is, tho, that it's kernel bound.. which means >CPU.. so unless you have tons of extra CPU to spare, this attack will >take your system to a "pause" until the attacker ceases. The name "stream.c" makes it sound like a local, not remote, DoS. Does it have to be done from inside the system to be effective? I would think that, if it came from the outside, it'd be harder to saturate the victim. I can think of ways to filter this by adding some stuff to IPFW. --Brett To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-stable" in the body of the message