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Date: Mon, 12 Nov 2018 17:21:53 +0100
From: Solar Designer <solar@...nwall.com>
To: lkrg-users@...ts.openwall.com
Subject: Re: LKRG 0.5

On Mon, Nov 12, 2018 at 08:03:31PM +0400, Ilya Matveychikov wrote:
> On Nov 12, 2018, at 7:51 PM, Solar Designer <solar@...nwall.com> wrote:
> > Is the khook_demo module you have loaded part of what you call a LKRG
> > bypass, or is it some unrelated demo/test you ran?  Is it part of what
> > caused the crash?
> 
> Quick answer about KHOOK. You can find it at github:
> https://github.com/milabs/khook

Thanks!

> > If it's part of the bypass, then that wouldn't count per our threat
> > model unless you loaded the module while under illegitimate root access
> > obtained via a kernel vulnerability exploit (in which case "ED" is meant
> > to trigger on module loading attempt).  Simple loading of kernel modules
> > (including custom ones) as legitimate root is allowed under LKRG -
> > including modules that would substantially modify system behavior (e.g.,
> > hook functions).
> 
> And yes, it's a part of bypass where the point is that having protection
> system (LKRG) and "malicious" module at the same level of abstraction worth
> nothing to do with the security.

You don't need a video to prove that indeed one can sort of "bypass"
LKRG by loading a kernel module.  This is a case of "works as intended".
Maybe such video can be useful as illustration to LKRG users on what
kind of protection not to expect from LKRG.  Maybe we also need to
improve our documentation in that respect - suggestions are welcome - if
some users would reasonably have different expectations from the way
LKRG is documented now.

LKRG "main" (unlike "experimental") doesn't include protection against
root in its threat model, except when said root access was just obtained
via a kernel vulnerability exploit.  I see nothing inconsistent in that.
Do you?  If so, what inconsistency do you see?

To me, that's a reasonable and consistent threat model, even if limited.

Alexander

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