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RE: Vulnerability of VMWare Virtual Machine?
From: "Burton Strauss" <Burton () FelisCatus org>
Date: Fri, 24 Mar 2006 15:01:28 -0600

It's PROBABLY the worst of both worlds... (and I'm speaking about personal
experiences w/ VMWare and Virtual PC, although I haven't tried to break in).

First off, an attack against a VM is basically a remote attack against
whatever OS that VM is running.  If it's a vulnerable one, it's vulnerable -
regardless of whether it's a VM or physical host.  Once you are in, you have
all the usual vectors to attack other hosts on that network, local privilege
escalation, whatever...

Where it gets different is that there are additional pieces in play when you
have a VM/Host combination, which might present you with other
opportunities:

(1) Although it's possible to disable all of the network protocols from a
NIC and dedicate it to a VM, you have to remember that the initial
processing is going to go through the host's network stack.  So an attack
against the driver or low level network stack - even though it's the VM's
NIC - is really against the host.

(2) Normally, if the NIC is operated in 'bridge' mode, then you have the
usual attack against the host and against the service or driver which
provides the bridge.  I'm not aware of any information on how secure that
service/driver is.  But if you could cause it to stack overflow, jump
addresses, execute shell code, it's an attack against the host, not the VM.

(3) Assuming you break into the VM, there is SOME communications between the
VM and the host.  See http://chitchat.at.infoseek.co.jp/vmware/ for some
information on the (undocumented) communications channel.  Whether you could
exploit this to attack the host is unknown.

Given those additional attack points, I think the only safe assumption is
that the VM is less secure (by some unknown amount) than a physical machine
running the same OS would be.  And you must realize that there is are some
potential attack points against the HOST also.

So I think prudence dictates that the HOST machine not be a key piece of
domain infrastructure (i.e. not your LDAP or AD server, etc.) and that you
keep all of the VMs up-to-date on security, just as you would for physical
machines subject to attack.


-----Burton



-----Original Message-----
From: Chavoux Luyt [mailto:chavoux () gmail com] 
Sent: Thursday, March 23, 2006 9:15 AM
To: security-basics () securityfocus com
Subject: Vulnerability of VMWare Virtual Machine?

Hi

I'm fairly new to virtual machines and would like to know more about their
vulnerability after reading the recent thread on creating an isolated
virtual LAN with 2 virtual machines. I'm using a VMware virtual machine
running WindowsXP SP2(as guest OS) on linux (host OS) for development. I can
connect to the virtual machine (shared folders) from the linux host using
konqueror & samba. I cannot access the linux host from the Windows virtual
machine, but I can connect to the internet and to the other (Windows) PC's
on the LAN (using their IP adresses). I have not bothered to join the domain
from the virtual machine nor installed the anti-virus/firewall software
running on all the other PC's on the LAN. I only use the virtual network
connection to copy data to and from the linux host.

I have two questions regarding the security risk of this setup...
1. The virtual machine is on a different (virtual) subnetwork to the rest of
the LAN... how vulnerable is it to attacks from the internet?
I.e. is it more vulnerable than the other Windows machines on the LAN that
have updated virus scanners and firewalls? (The whole LAN is behind a
firewall as well).
2. If the virtual machine itself get compromised, it is not such a big
problem. However, how vulnerable would the other windows machines on the LAN
be to attacks from a compromised virtual machine? Basically, if I'm not
worried about the data on the virtual machine, should I bother to make it
secure?

Thanks
Chavoux

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---------------------------------------------------------------------------
EARN A MASTER OF SCIENCE IN INFORMATION ASSURANCE - ONLINE
The Norwich University program offers unparalleled Infosec management 
education and the case study affords you unmatched consulting experience. 
Tailor your education to your own professional goals with degree 
customizations including Emergency Management, Business Continuity Planning, 
Computer Emergency Response Teams, and Digital Investigations. 

http://www.msia.norwich.edu/secfocus
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