From owner-freebsd-security@FreeBSD.ORG Thu Jan 28 23:21:43 2010 Return-Path: Delivered-To: freebsd-security@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 69BC51065694 for ; Thu, 28 Jan 2010 23:21:43 +0000 (UTC) (envelope-from dillon@apollo.backplane.com) Received: from apollo.backplane.com (apollo.backplane.com [216.240.41.2]) by mx1.freebsd.org (Postfix) with ESMTP id 34E858FC14 for ; Thu, 28 Jan 2010 23:21:43 +0000 (UTC) Received: from apollo.backplane.com (localhost [127.0.0.1]) by apollo.backplane.com (8.14.4/8.14.1) with ESMTP id o0SNBWeh003679 for ; Thu, 28 Jan 2010 15:11:33 -0800 (PST) Received: (from dillon@localhost) by apollo.backplane.com (8.14.4/8.13.4/Submit) id o0SNBWp4003678; Thu, 28 Jan 2010 15:11:32 -0800 (PST) Date: Thu, 28 Jan 2010 15:11:32 -0800 (PST) From: Matthew Dillon Message-Id: <201001282311.o0SNBWp4003678@apollo.backplane.com> To: freebsd-security@freebsd.org References: <20100128182413.GI892@noncombatant.org> <9d972bed1001281324r29b4b93bw9ec5bc522d0e2764@mail.gmail.com> <20100128224022.396588dc@gumby.homeunix.com> Subject: Re: PHK's MD5 might not be slow enough anymore X-BeenThere: freebsd-security@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: "Security issues \[members-only posting\]" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 28 Jan 2010 23:21:43 -0000 Just give up and turn off tunneled plaintext passwords over the network. No (non-kerberos) telnetd, rlogind, (non anonymous) ftpd, etc. Just run sshd and put this in your sshd_config: # To disable tunneled clear text passwords, change to no here! PasswordAuthentication no Local passwords can still be used for things like a (restricted) sudo, console root logins, and X/xdm. Disallowing remote passworded logins removes the primary attack vector, which is over the network. You'd probably want to adjust /etc/login.access too since for some reason beyond my comprehension /usr/bin/login can be run from pty's to cross-login locally (with a password). So even if the attacker knows the password he is SOL without physical access. -- The problem with stolen master.passwd files is that you often don't know the file has been stolen until the hacker actually starts using the compromised accounts. In otherwords, the hacker has as much time as he wants to break the file before having to worry about someone reacting to it. This makes the concept of multiplying the analysis cost almost completely worthless above and beyond everything else mentioned. Mostly these protections against stolen master.passwd files aren't so much to protect the machine against being hacked (since it was hacked already to get the file in the first place), but instead to reduce the work involved when cleaning up after a hack incident. It's best to limit the damage by making the stolen file simply not be useful to a remote attacker. -Matt Matthew Dillon