Re: [malware-list] TALPA - a threat model? well sorta.

[Mihai DonÈu]

On Thursday 14 August 2008, Press, Jonathan wrote:
> > On Wednesday 13 August 2008, Andi Kleen wrote:
> > > On Wed, Aug 13, 2008 at 12:36:15PM -0400, Eric Paris wrote:
> > >
> > > I miss a clear answer to the question: is this
> > > supposed to protect against malware injected as root or not?
> >
> > I honestly don't think we should worry about root. Sure, if the AV
> > scanner happens to catch something (as a consequence of it's
> > implementation), then very well. But designing an antimalware solution
> > which assumes the root is compromised will throw us into security talks
> > for years and I don't think we'll live to hear the end of them.
> >
> > We should focus on the regular users and fix (if needed) the current
> > userland apps (ie. the ones that need root access to do their job). For
> > anymore than that we'll need a super user that supervises root. And then
> > another one.
>
> I think that some people are missing the important point of Eric's recent
> original statement of the "threat model".  Whether we move further in the
> direction of other security protections or not, we are currently talking
> about providing a mechanism for basic AV product to do their job, and the
> job we are talking about is scanning files when they are about to be used
> and might cause harm, or have just been created and we want to make sure
> they are OK.  That is, the AV products that we are talking about in this
> context don't do anything else other than scan files.

I see. Well, as long as everyone sticks to _just_ the file scan. To be honest, 
the only immediate use of the patch that is/was in question, is a "natural" 
scanner for file servers (Samba, NFS etc). 7v5w7go9ub0o, however, might have 
some more ideas. :)

I admit and I apologize, I got pretty worked up when people started asking 
questions like: "how do we protect the file scanner", when the answer should 
have been obvious: the way we protect any other daemon (service) today, by 
means of chmod/chown.

> With that in mind, there is no difference between scanning files being
> accessed/executed/created by root and the same for any other users.  And in
> fact, to the extent that we claim at all to have a somewhat complete
> protection in that realm, excluding root will completely blow that protect
> out of the water and make it essentially useless.
>
> > I think we need to define the 'desktop user' and provide a decent
> > protection mechanism for his common activities (edit documents, listen
> > music, navigate the web, see movies, run scripts which change the IM
> > status etc). For the rest, there are two possibilities:
> >
> >     1. education (_extremely_ important);
>
> It's like abstinence education...it sounds good, at least to some, but it
> doesn't work.  In a way, that's the whole point.  There are millions of
> users.  It doesn't take many who missed the class to create an outbreak
> that does real damage.  It goes back to the medical analogy.  Do you spray
> the swamps for the mosquitoes that carry Eastern Equine Encephalitis, or do
> you knock on everyone's door and tell them not to go near the swamps, and
> hope that everyone's home when you're in their neighborhood?
>
> > I don't think there will ever be an AV product using the marketing line:
> > "it allows you to run your favorite rootkit and enjoy the pretty text it
> > shows, with no worries".
>
> You are right...  Complete rootkit protection is a whole other area not
> fundamentally addressed by a scan.  So let's not create a straw man about
> the things we don't claim to do and then knock the products because we
> don't do them.

-- 
Mihai DonÈu
Again, this mail == my own opinion
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