From owner-freebsd-security Sun Oct 17 23:48: 5 1999 Delivered-To: freebsd-security@freebsd.org Received: from fever.semiotek.com (H253.C225.tor.velocet.net [216.126.82.253]) by hub.freebsd.org (Postfix) with ESMTP id 3951014A2A for ; Sun, 17 Oct 1999 23:47:51 -0700 (PDT) (envelope-from jread@fever.semiotek.com) Received: (from jread@localhost) by fever.semiotek.com (8.9.3/8.9.3) id CAA00790; Mon, 18 Oct 1999 02:47:05 -0400 (EDT) (envelope-from jread) Date: Mon, 18 Oct 1999 02:47:05 -0400 From: Justin Wells To: Doug Cc: Justin Wells , Antoine Beaupre , Mike Nowlin , "Rashid N. Achilov" , freebsd-security@FreeBSD.ORG Subject: Re: kern.securelevel and X Message-ID: <19991018024704.A512@semiotek.com> References: <14343.23571.679909.243732@blm30.IRO.UMontreal.CA> <19991017012750.A812@fever.semiotek.com> <380A1E2C.CCA326F5@gorean.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii X-Mailer: Mutt 1.0pre3i In-Reply-To: <380A1E2C.CCA326F5@gorean.org> Sender: owner-freebsd-security@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.org On Sun, Oct 17, 1999 at 12:06:20PM -0700, Doug wrote: > > The problem with securelevel, in my mind, is that an attacker who > > got root would simply write stuff into the /etc/rc scripts and then > > force the machine to reboot. ... > > Does anyone have any clever solutions? > > Mount / read only. That is clever. I even thought it was work, and tried it. However, there are a couple of problems: 1) securelevel does not stop root from remounting / read-write, since mount is specifically excepted (I tried it too, I was able to do a "mount -u -o rw /" at securelevel 3 as root) 2) mounting / read only is nasty anyway, since you lose the ability to chown /dev/tty* which makes some things act very weird (many programs expect you will own your tty or else they get angry) So, any more clever suggestions? Maybe at securelevel 3 you should not be allowed to change the mount table either (no mounting and no umounting, period). That and a solution to the tty problem would make things fairly secure. Justin To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-security" in the body of the message