Garrett: What is an SBAT and why does everyone suddenly care

Matthew Garrett describesthe role of the Secure Boot Advanced Targeting mechanism and how itplayed into the recent Windows upgrade problems.

So why is this suddenly relevant? SBAT was developedcollaboratively between the Linux community and Microsoft, andMicrosoft chose to push a Windows update that told systems not totrust versions of grub with a security generation below a certainlevel. This was because those versions of grub had genuine securityvulnerabilities that would allow an attacker to compromise theWindows secure boot chain, and we've seen real world examples ofmalware wanting to do that.