Re: [Xen-devel] Re: Module loading in unpriveledged domains

[David Hopwood <david.nospam.hopwood@xxxxxxxxxxxxxxxx>]

Nuutti Kotivuori wrote:
> David Hopwood wrote:
>
> > True, unless there are bugs that cause different behaviour depending
> > on whether a module is compiled-in or loaded (such as
> > <http://lists.jammed.com/linux-security-module/2003/12/0012.html>).
> > Nevertheless enabling loadable modules may allow a greater
> > proportion of script kiddies to be capable of exploiting any given
> > bug.
> >
> > This is all the same as in standard Linux, so perhaps I should have
> > said: enable loadable modules iff you would do so in standard Linux.
> That's a bit of an odd comment I think.
>
> Enabling module loading has security implications for the actual Linux
> system being exploited - eg. either the physical machine in a
> standalone case, or a Xen guest virtual machine.
>
> But the original question was not about the security of that machine,
> but about the possibility of escalation of that exploit into other
> Xen guests or the domain 0 on the same physical machine.
If there is no exploit, then there is no possibility of escalation.
On a physical machine running Linux on Xen where an attacker only has
direct access to Linux user-mode processes, the attacker has two layers
that must both be exploited: Linux and Xen. Obviously, bugs and
misconfigured settings in both Linux and Xen are therefore relevant
to the security of the physical machine.

--
David Hopwood <david.nospam.hopwood@xxxxxxxxxxxxxxxx>



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