From owner-freebsd-security Thu Jan 25 03:40:29 1996 Return-Path: owner-security Received: (from root@localhost) by freefall.freebsd.org (8.7.3/8.7.3) id DAA18529 for security-outgoing; Thu, 25 Jan 1996 03:40:29 -0800 (PST) Received: from skiddaw.elsevier.co.uk (skiddaw.elsevier.co.uk [193.131.222.60]) by freefall.freebsd.org (8.7.3/8.7.3) with SMTP id DAA18524 for ; Thu, 25 Jan 1996 03:40:24 -0800 (PST) Received: from snowdon.elsevier.co.uk (snowdon.elsevier.co.uk [193.131.197.164]) by skiddaw.elsevier.co.uk (8.6.12/8.6.12) with ESMTP id LAA02746 for ; Thu, 25 Jan 1996 11:38:35 GMT Received: from cadair.elsevier.co.uk (actually host cadair) by snowdon with SMTP (PP); Thu, 25 Jan 1996 11:38:45 +0000 Received: (from dpr@localhost) by cadair.elsevier.co.uk (8.6.12/8.6.12) id LAA24328 for security@FreeBSD.org; Thu, 25 Jan 1996 11:38:48 GMT From: Paul Richards Message-Id: <199601251138.LAA24328@cadair.elsevier.co.uk> Subject: bin owned files To: security@FreeBSD.org Date: Thu, 25 Jan 1996 11:38:47 +0000 (GMT) X-Mailer: ELM [version 2.4 PL24] Content-Type: text Sender: owner-security@FreeBSD.org Precedence: bulk I'l summarise all the point against what I said briefly. Getting bin access does not give you root access. As bin you can't touch root files and you can't create a suid root file either. Users can't give away ownership. Therefore, the only way to get root access from bin is to replace, say, /bin/sh with a program that creates a suid root sh *when it is run by root*. If you log in as root and don't realise that there has been a compromise of bin then that is your problem but in and of itself a bin compromise is safer than a root compromise for the reasons I previously explained. All other arguments relate to NFS and I refuse to even discuss NFS in this context. If you crack root anywhere on an NFS system then the whole system is compromised and while making things owned by root makes it a little harder it is no protection. I can masquerade as many other users and find other ways to do what I want. The whole point is, there *was* a root break-in, the fact that it wasn't the actual server box is not an issue. NFS cannot be regarded as a number of separate machines from a security context, a compromise on one is a compromise on them all. -- Paul Richards. Originative Solutions Ltd. Internet: paul@netcraft.co.uk, http://www.netcraft.co.uk Phone: 0370 462071 (Mobile), +44 1225 447500 (work)