this post was submitted on 06 Dec 2023
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[–] linearchaos 11 points 11 months ago (1 children)

They need to be able to place a malicious file in EFI boot partition or in an unsigned section of a firmware update. Holes in the libraries that parse images for display on preboot.

[–] [email protected] 3 points 11 months ago (1 children)

What if I disable UEFI splash screen? I always do that if possible. Not due to this, but because I prefer a bunch of text over a lame logo.

[–] linearchaos 5 points 11 months ago (1 children)

No way to know. It depends on how whoever did your firmware handled it. The idea is that there's an overflow or something in the image parser. If the person writing your firmware code still parses the image even if it's not displayed, you'd still get the pointy end. (and at that point, they're bypassing secure boot)

Don't sweat it too much, the file has to get there somehow before it can even be an issue. So someone needs to write to your UEFI partition or get you to flash a bad bios. It's just an inside vector not a direct attack. I'll be good for people to update their damn image processing, but the likely hood of getting shived in the wild is pretty low.

[–] [email protected] 2 points 11 months ago

I wonder.. could one put their UEFI partition on a flash drive, then remove after booting? Or just dismount the partition, but physical separation sounds better