oss-sec mailing list archives

Re: lockdown bypass on mainline kernel for loading unsigned modules


From: John Haxby <john.haxby () oracle com>
Date: Mon, 15 Jun 2020 17:22:27 +0100

Hi Jason,


On 15 Jun 2020, at 11:26, Jason A. Donenfeld <Jason () zx2c4 com> wrote:

Hi everyone,

Yesterday, I found a lockdown bypass in Ubuntu 18.04's kernel using
ACPI table tricks via the efi ssdt variable [1]. Today I found another
one that's a bit easier to exploit and appears to be unpatched on
mainline, using acpi_configfs to inject an ACPI table. The tricks are
basically the same as the first one, but this one appears to be
unpatched, at least on my test machine. Explanation is in the header
of the PoC:

https://git.zx2c4.com/american-unsigned-language/tree/american-unsigned-language-2.sh

I need to get some sleep, but if nobody posts a patch in the
meanwhile, I'll try to post a fix tomorrow.

Jason

[1] https://www.openwall.com/lists/oss-security/2020/06/14/1


This looks CVE-worthy.   Are you going to ask for a CVE for it?

jch

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