From mboxrd@z Thu Jan 1 00:00:00 1970 From: Matthew Garrett Subject: Re: [RFC] Second attempt at kernel secure boot support Date: Sat, 3 Nov 2012 00:22:44 +0000 Message-ID: <20121103002244.GC18691@srcf.ucam.org> References: <20121101202701.GB20817@xo-6d-61-c0.localdomain> <5092E361.7080901@genband.com> <20121102163302.GA6080@elf.ucw.cz> <1351875164.2439.42.camel@dabdike.int.hansenpartnership.com> <20121102165456.GB9997@srcf.ucam.org> <1351878511.2439.44.camel@dabdike.int.hansenpartnership.com> <20121102175416.GA11816@srcf.ucam.org> <1351879058.2439.46.camel@dabdike.int.hansenpartnership.com> <20121102180458.GA12052@srcf.ucam.org> <1351899503.2439.49.camel@dabdike.int.hansenpartnership.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <1351899503.2439.49.camel@dabdike.int.hansenpartnership.com> Sender: linux-security-module-owner@vger.kernel.org To: James Bottomley Cc: Pavel Machek , Chris Friesen , Eric Paris , Jiri Kosina , Oliver Neukum , Alan Cox , Josh Boyer , linux-kernel@vger.kernel.org, linux-security-module@vger.kernel.org, linux-efi@vger.kernel.org List-Id: linux-efi@vger.kernel.org On Fri, Nov 02, 2012 at 11:38:23PM +0000, James Bottomley wrote: > On Fri, 2012-11-02 at 18:04 +0000, Matthew Garrett wrote: > > A user runs a binary that elevates itself to admin. Absent any flaws in > > Windows (cough), that should be all it can do in a Secure Boot world. > > But if you can drop a small trusted Linux system in there and use that > > to boot a compromised Windows kernel, it can make itself persistent. > > We seem to be talking past each other. Assume you managed to install a > Linux boot system on the windows machine. If the linux boot requires > present user on first boot (either because the key of the bootloader > isn't in db or because the MOK database isn't initialised), you still > don't have a compromise because the loader won't start automatically. Why would an attacker use one of those Linux systems? There's going to be plenty available that don't have that restriction. -- Matthew Garrett | mjg59@srcf.ucam.org