From: Dave Howe (David.Howe@ansgroup.co.uk)
Date: Fri Jan 25 2008 - 18:46:00 EST
Albert R. Campa wrote:
> We have some admins setting up some VMs on an ESX server and they
> have the idea of setting up 1host server with multiple VMs and on
> some of these VMs they want physical NICs connected to our main LAN
> and other VMs they want physical wires connected to a DMZ lan.
>
> Normally this would be almost bridging the two networks and bad
> practice overall. An explanation from an SA is that virtual switches
> are used on the ESX host and this seperates the physical connection
> to our main LAN and this DMZ lan.
>
> This does not sound like good practice but is there documentation to
> back that up or in your experience have you been able to exploit this
> type of configuration?
I would consider this no better or worse than sharing a single
physical switch with vlans in different domains - if the core os could
be compromised, it would bridge across the security domains, but the
same would be true of a firewall device between the two (which is after
all convention) - apart from the fact that I doubt ESX is designed as a
security device.
I would be more concerned that the techniques for detecting that the
os is inside an emulated (VMWare) environment, and the extensions used
by the VMware tools, could be exploited to run code on the native cpu.
No direct reason to expect this is true, but similarly, no direct reason
to believe it is impossible either.
David Howe
Senior SysCare Engineer
david.howe@ansgroup.co.uk
Office number: 0161 227 1010
Fax: 0161 227 1020
ANS group plc
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Manchester Science Park
Manchester
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