Re: [SECURITY PATCH 00/28] Multiple GRUB2 vulnerabilities - BootHole

[John Paul Adrian Glaubitz]

Hi Dimitri!

On 7/29/20 11:20 PM, Dimitri John Ledkov wrote:
> Disclosures were done to a subset of binary distributions that have a
> trust path to shims signed with Microsoft UEFI CA 2011 db key. Arch
> Linux does not provide shim-signed with keys controlled by Arch Linux
> and it doesn't provide pre-signed secureboot kernels.
> 
> Reading Arch Linux documentation it seems that Fedora's shim is used
> together with self-signed Mok Keys.
> 
> Mitigation strategy for Arch Linux will then be quite different to
> everyone else:
> 
> 1) Update to new shim from fedora when available, as previous ones are
> going to be revoked by the dbxupdate from uefi.org
> 2) Patch Archlinux grub
> 3) Patch Archilinux kernel for lockdown bypass
> 4) Generate new MOK key, enroll it into MOK
> 5) Sign patched grub/kernel with the new MOK key
> 6) Provide instructions for users to revoke their old key via MOKX,
> i.e. use mokutil --mokx --import existing cert; or for example delete
> the old key from MOK with --delete old-cert.der
> 
> This is just a rough guideline, please analyze how signing keys are
> controlled and used on typical Arch Linux deployment and adjust things
> to taste.
> 
> The key point is to rotate the signing key used for
> shim/grub/kernel/fwupd, only use the new key to sign fixed things, and
> ensure that old key is no longer trusted (removed from MOK, or added
> to MOKX).

Thanks for describing the detailed procedure, very informative.

Adrian

-- 
 .''`.  John Paul Adrian Glaubitz
: :' :  Debian Developer - glaubitz@debian.org
`. `'   Freie Universitaet Berlin - glaubitz@physik.fu-berlin.de
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