Windows 7 Forums

Welcome to Windows 7 Forums. Our forum is dedicated to helping you find support and solutions for any problems regarding your Windows 7 PC be it Dell, HP, Acer, Asus or a custom build. We also provide an extensive Windows 7 tutorial section that covers a wide range of tips and tricks.

Windows 7: Vulnerability in Virtual PC?

16 Mar 2010   #1

Vulnerability in Virtual PC?

Earlier today, Core Security Technologies issued a security advisory for our Virtual PC (VPC) software. The advisory calls out a proof of concept where the virtual machine monitor allows memory pages above the 2GB level to be read from or written to by user-space programs running within a guest operating system. The advisory explicitly calls into question the effectiveness of many of the security hardening features of Windows, including DEP, SafeSEH, and ASLR. Folks are already starting to ask questions about this advisory, so I thought it would be best to answer them here.

First and foremost, customers should rest assured that this advisory does not affect the security of Windows 7 systems directly. The security safeguards (DEP, ASLR, SafeSEH, etc.) that are in place remain effective at helping protect users from malware on that system. In addition, Our Windows Server virtualization technology, Hyper-V, is also not affected by this advisory. Applications running inside a Hyper-V guest continue to benefit from these same security safeguards.

The functionality that Core calls out is not an actual vulnerability per se. Instead, they are describing a way for an attacker to more easily exploit security vulnerabilities that must already be present on the system. It's a subtle point, but one that folks should really understand. The protection mechanisms that are present in the Windows kernel are rendered less effective inside of a virtual machine as opposed to a physical machine. There is no vulnerability introduced, just a loss of certain security protection mechanisms.

The functionality described only affects the guest operating system that is running within a Virtual PC environment. In practice, the guest operating system in a Virtual PC environment is typically Windows XP as part of Windows XP Mode. Of the safeguards Core calls out, it should be noted that only DEP is available in Windows XP SP3; Windows XP doesn't contain SafeSEH or ASLR. The net result? An attacker can only exploit a vulnerable application running "inside" the guest virtual machine on Windows XP, rather than Windows 7!

We believe that Windows XP Mode and Windows Virtual PC are great bridging strategies to help customers who have legacy applications get up and running on Windows 7. For those customers who need Windows XP Mode, they should look to install only the required subset of applications that need Windows XP in order to function properly while planning to move those applications to Windows 7 in the future.

One final point, whether the version of Windows you are running is virtualized or running physically on a computer, it's equally important to follow sound security practices. You should make sure your firewall is enabled, that you have anti-virus software installed, and that you keep your software up to date through automatic updates. For more information on how to protect your PC, visit


My System SpecsSystem Spec

 Vulnerability in Virtual PC?

Thread Tools Search this Thread
Search this Thread:

Advanced Search

Similar help and support threads
Thread Forum
How to Create a Win95 Virtual Machine in Windows Virtual PC
Hi, first post here. I have Win XP mode running in Win virtual pc on my Win 7 Pro tower. I have been given an original and unopened Win95 pack containing a Win95 v4.0.950B Nov96 CD with USB support and an IE4 CD. I think I understand from Brinks "How to create a virtual machine in windows virtual...
Windows Virtual PC - Connect Virtual Machine to Network
How to Connect Windows Virtual PC to the Network This will show you how to connect Windows Virtual PC to your network so that your created virtual machine or XP Mode will be able to access the internet. For more information, see: Networking in Windows Virtual PC - Windows Virtual PC -...
Can I retrieve files on virtual machine even if cannot start Virtual
I installed Windows XP mode on my PC 14 months ago. Everything was working fine . One dayabout 6 months ago, I could not start my virtual machine. I stupidly reinstalled XP mode. Result I lost all my files of the programs running in XP (autosketch). My installation allowed me to reinstall...
How do I eliminate a virtual disk in a virtual machine?
Instead of using XP mode which is not available in Windows 7 Home Premium, I installed a virtual machine and installed Windows XP prof from an installation DVD. My HD has three partions, two of about 80 GB and one of 340 GB. The CPU is Intel core i5 with 3 GB Ram. It works fine, I have XP in a...
Can I load up my linux partition in Virtual Box or any Virtual Machine
Hi, I am new to virtual machine. I have Windows 7 and Ubuntu dual boot on my single harddisk right now. Windows 7 on sda1, ubuntu on sda2. Just wondering, could I use any virtual machine software, virtualbox or virtual PC or vmware, to run my ubuntu on sda2 under windows 7 or to run my...
Windows Virtual PC - Change Virtual Machine Settings
How to Change Virtual Machine Settings in Windows Virtual PC This will show you how to change a Windows Virtual PC virtual machine's settings in Windows 7. To create a virtual machine or install Windows XP Mode, you will need to download and install the 32-bit (x86) or 64-bit (x64) version of...

Our Sites

Site Links

About Us

Find Us

Windows 7 Forums is an independent web site and has not been authorized, sponsored, or otherwise approved by Microsoft Corporation. "Windows 7" and related materials are trademarks of Microsoft Corp.

Designer Media Ltd

All times are GMT -5. The time now is 15:00.

Twitter Facebook Google+

Windows 7 Forums

Seven Forums Android App Seven Forums IOS App