There are several ways to exploit LogoFAIL. Remote attacks work by first exploiting an unpatched vulnerability in a browser, media player, or other app and using the administrative control gained to replace the legitimate logo image processed early in the boot process with an identical-looking one that exploits a parser flaw. The other way is to gain brief access to a vulnerable device while it’s unlocked and replace the legitimate image file with a malicious one.
In short, the adversary requires elevated access to replace a file on the EFI partition. In this case, you should consider the machine compromised with or without this flaw.
You weren’t hoping that Secure Boot saves your ass, were you?
The worst part it persists through reinstalls (if i understood correctly)
It can outlast those too.
In many of these cases, however, it’s still possible to run a software tool freely available from the IBV or device vendor website that reflashes the firmware from the OS. To pass security checks, the tool installs the same cryptographically signed UEFI firmware already in use, with only the logo image, which doesn’t require a valid digital signature, changed.
Since the EFI partition is unencrypted, physical access would do the trick here too, even with every firmware/software security measure.
True, but this was the case without this finding, wasn’t it? With write access to the EFI you could replace the boot loader and do whatever you please.
So if I have my computer set that it needs a sudo password for most changes am I good?
Yes, that’s my understanding. A normal user cannot do this. (And of course, an attacker shouldn’t not control a local user in the first place.)
Physical access is also a risk, but physical access trumps everything.
Thanks for the answer. Unless my dog learns how to code I think I’m safe from anyone getting physical access
replace a file on the EFI partition.
Doesn’t this mean that secure boot would save your ass? If you verify that the boot files are signed (secure boot) then you can’t boot these modified files or am I missing something?
If it can execute in ram (as far as I understand, they’ve been talking about fileless attacks, so… Possible?), it can just inject whatever
Addit: also, sucure boot on most systems, well, sucks, unless you remove m$ keys and flash yours, at least. The thing is, they signed shim and whatever was the alternative chainable bootloader (mako or smth?) effectively rendering the whole thing useless; also there was a grub binary distributed as part of some kaspersky’s livecd-s with unlocked config, so, yet again, load whatever tf you want
Last time I enabled secure boot it was with a unified kernel image, there was nothing on the EFI partition that was unsigned.
Idk about the default shim setup but using dracut with uki, rolled keys and luks it’d be secure.
After this you’re protected from offline attacks only though, unless you sign the UKI on a different device any program with root could still sign the modified images itself but no one could do an Evil Maid Attack or similar.
If I can replace a file in your EFI, how hard would it be to sign the same file.
The idea is also that a compromised system will remains compromised after all storage drives are removed.
