Hands-on: Windows Defender Application Guard

Microsoft announced more than a year ago a new feature coming to Windows 10 allowing Microsoft Edge to run in Isolated User Mode. This needs to be configured before users can access the feature, this can be done through Group Policy. For more information: https://docs.microsoft.com/en-us/windows/threat-protection/windows-defender-application-guard/configure-wd-app-guard

In the chart below you can see Microsoft’s comparison of Microsoft Edge and Edge with Windows Defender Application Guard:

 

I installed a Windows 10  Enterprise Insider Preview Build 16278 on a computer, enabled Application Guard and started experimenting.

I started out by enabling some useful Policies settings, that can be found here “Administrative Templates -> Windows Components -> Windows Defender Application Guard”.

Allow data persistence for Windows Defender Application Guard: Saves user downloaded files and other items (such as, cookies, Favorites and so on) for use in future Application Guard Sessions. Enabled this feature to give end-users a smoother experience when using Application Guard. There will be some confusion on how to access files that were downloaded in an Application Guard session. A session can be reset by using “Reset-ApplicationGuard”, the command is not available in the current build I’m running.

Configure Windows Defender Application Guard Clipboard Settings: Enabling this settings give you several options. It is not recommended to enable copying data data from the host to the isolated session, enabling this might give a compromised Application Guard session access to the host’ clipboard. I enabled with “Enable clipboard operation from an isolated session to the host” and then specified the value 1: Allows text copying (2 = Allow image copying, 3 = Allows both text and image).

Configure Windows Defender Application Guard Print settings:

By default you can’t print from an Application Guard session. In this policy you can chose from 15 different options to allow printing from the session to local, XPS, PDF and network printers. In this scenario I only chose to allow printing to PDF for now.

I also had to configure settings in “Administrative Templates -> Network -> Network Isolation” in order to fully configure Windows Defender Application Guard-

I specified “Enterprise resource domains hosted in the cloud”, which are sites that I fully trust and allow to run in a normal browser session, for these testing purposes I specified 2 sites, pay close attention to the separation of the 2 sites I specified, instead of a comma-separation these sites are separated by a pipe (|)character. It also supports wildcard scenarios by specifying DOT character before domain name.

 

After a reboot I was ready to launch Microsoft Edge and give the feature a try. My first attempt to launch an Application Guard session (directly from Microsoft Edge, which was now an option):

It took 5 minutes for initial session to launch my first session, patience is a virtue:

When launching the first thing I notice is my Favorites are missing, just as expected:

I started browsing a site that’s on the list of Enterprise Resources and it launched just as expected in a normal session where I was able to interact with one of the sites I trust, screenshot:

 

The second I access a site that’s not on the list of Enterprise resources it opens in a new instance of Microsoft Edge that has another icon on the toolbar and is protected, as expected:

Trying to copy data from the host into the Application Guard session gives me a warning, also as expected:

Trying to paste data from the session to Notepad works just fine without any warning.

Overall, this feature is very secure and provides a way for users to browse the internet without risking that the host will be compromised, currently it’s not the most efficient way and Microsoft is looking into integrating add-ins and let Favorites work across the Isolated and Normal session.

 

Windows Defender Application Guard is set to release with the Windows 10 Fall Creator’s Update.