News

Microsoft Defender Application Guard for Office Hits Public Preview

• By Kurt Mackie
• August 24, 2020

Aimed at top-tier Microsoft 365 subscribers, the Microsoft Defender Application Guard for Office solution (also called "Application Guard for Office") became available for public preview this week.

The solution is designed to "isolate untrusted documents away from the system," Microsoft explained in a document on the topic. It adds a virtualized container or "sandbox" for users of Microsoft 365 productivity applications, such as Excel, PowerPoint and Word. It lets end users safely view and open attached Microsoft 365 application files in e-mails. Any scripts (macros or ActiveX controls) or malicious links in those files, when activated, don't escape the sandbox.

Application Guard for Office, while seemingly useful for all Office users, is just aimed at Microsoft 365 E5 plan subscribers. The licensing requirements for the product, when generally released, will be subscriptions to "Microsoft 365 E5 or Microsoft 365 E5 Security" licensing.

Requirements for testing the preview include having Windows 10 version 2004 (build 19041) Enterprise edition and Office 365 version 2008 (build 16.0.13212 or later). In addition, security update KB4566782 needs to be installed. There's also hardware requirements for client devices, such as Intel Core i5 or equivalent at minimum, 8GB of RAM and 10GB of storage space.

End users get a warning pop-up box when documents get opened using Application Guard for Office. An opened document will show another pop-up notice in the ribbon menu, and there will be a shield icon displayed in the taskbar. However, it's still possible for end users to remove the Application Guard for Office protection on a document if they trust the source.

In addition, it's possible for users to save a copy of an untrusted file, which lets them work on it in the container. Untrusted files from outside the organization appear as "read-only" files to end users.

IT pros can set certain policies for Application Guard for Office, such as disabling copy-and-paste actions, restricting printing and turning off app access to a device's microphone and camera.

Back in February, this solution was at the "limited preview" stage and went by the name "Application Guard for Office 365 ProPlus." (In April, Microsoft switched the Office 365 ProPlus product name to "Microsoft 365 Apps for enterprise," by the way.) Now this security solution is called Microsoft Defender Application Guard for Office, but it's just for top-of the-line Microsoft 365 E5 subscribers.

When Application Guard for Office reaches general availability, it'll be turned off by default for Microsoft 365 E5 tenancies, the announcement indicated. A listing in the Microsoft 365 Roadmap showed Application Guard for Office getting a product release in December.