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Re: ESX Vmware Physically connected to different segments
From: Enno Rey <erey () ernw de>
Date: Mon, 28 Jan 2008 22:04:46 +0100

David,

look at the security advisories VMware issued in the last six months.
Most of them had at least one "full compromise of host by attack from guest" (for ESX) in them. And there are quite 
some people out there who think this thing is long from being finished...

For some more details and discussion you might look at 

http://www.ernw.de/content/e7/e181/e987/download989/erey_virtualization_v099r_ger.pdf

thanks,

Enno



On Mon, Jan 28, 2008 at 03:32:41PM -0500, David M. Zendzian wrote:
Yes it does make you think twice when considering such a design, however 
I am not familiar with exploits at a guest domain that would effect the 
host specifically. While yes in 'theory' there could be some kernel hook 
that could allow a guest to access the host server, and I hate to be in 
a situation when one arrives; however, the same argument also applies to 
shared virtual web hosts, but only the largest companies have dedicated 
hosts for every domain, there will always be sharing happening which is 
why virtual environments are growing in popularity.

Would it not be better to examine the hooks in systems that allow 
communication / buffers / etc in virtual environments and help ensure 
that they are done correctly? I know this is not really possible with 
VMWare, but with Xen & other systems where the code is available the 
issues can at least be investigated.

Now if someone has code (links/docs/etc) available the detail attacks on 
guests effecting hosts (DOS not included, exploits taking control of 
services of a host from a guest, or accessing network or resources not 
setup for that guest), then please post them to the list so we can 
discuss the issues and how to address them.

These same questions might also be applied to VLANs or other types of 
virtualization techniques that allow for greater use of the devices we 
have available. While there are fun ways to attack network vlans to 
access security domains outside of configured settings, it is the 
disclosure of these techniques that allowed for providers to secure the 
tools to a point where I know of no business I've ever worked with have 
dedicated network devices for every network. While I have seen different 
equipment on "DMZ vs Internal" networks, most still use VLAN security to 
segment those as well (it's a $ thing & usually a complexity thing, more 
parts means more people to manage, understand, change w/ out breaking, etc).

I believe there are ways of deploying virtual technology that may not 
prevent the theoretical attack, at least provide protection against the 
common attacks and provide for a viable solution for the small business' 
I work with.

The only way to be secure is to unplug, the rest of us have to work for 
a living :)

David

Kurt Buff wrote:
Even if everything is configured properly, mixing security domains in
a virtual hosting is a capital mistake.

That's because the underlying host is also vulnerable, and attacks
against a guest OS in an untrusted domain can be leveraged against the
host, and from there *all* guest OSes are toast, or near to it.

Don't do it, ever.

Kurt

On Jan 28, 2008 5:08 AM, Loupe, Jeffrey J <JLoupe () whitneybank com> wrote:
 
If everything is setup properly this configuration should be secure. The
problem comes with misconfiguration. It's exceedingly easy for a
careless admin to connect a vNic to the wrong vSwitch and allow traffic
meant for the DMZ onto the trusted network. In general we disallow this
practice unless only one or two trusted admins have control of the box.
Even then, we audit the configuration frequently.

-J

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-- 
Enno Rey

Check out www.troopers08.org!


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