Office 365 Safe Documents and Application Guard Previews Announced

Microsoft on Wednesday announced previews of two new Office document security protections for Office 365 E5 subscribers that aim to block malicious payloads.

One of the previews is a new Safe Documents protection option. Safe Documents uses Microsoft's Intelligent Security Graph service to automatically check Office documents (Excel, PowerPoint, Word etc.) "against known risks and threat profiles" before users open them. It's a step up from the current "Protected View" scheme that dates back to Office 2010, which allows users to decide on whether to trust a document or not by turning on editing. It's possible for such trusted documents to contain unsafe macros or malicious links.

The other preview is a new Application Guard for Office 365 ProPlus applications, which isolates those Office applications on a user's system by launching them in a "micro" virtual machine. Microsoft already has a Windows Defender Application Guard for the Microsoft Edge browser to protect users from Web site-based malware, but adding such sandbox protections for Office 365 ProPlus apps is new.

Safe Documents and Application Guard for Office 365 ProPlus are both described as using "some of the best of Windows 10, Office 365 ProPlus, and Microsoft Defender ATP [Advanced Threat Protection]" capabilities, per the announcement. That's a hint at the sort of licensing that will be required.

Both previews may be available for testing. A Microsoft 365 Roadmap item somewhat ambiguously stated that "Safe Documents is now available in public preview, rolled out by Feb 28th." Microsoft's announcement stated that Safe Documents will be "initially available for tenants in the U.S., U.K., and European Union" at some point.

The Safe Documents option can be activated using Office 365 Advanced Threat Protection's (ATP's) Safe Attachments feature, per this Microsoft document description.

There doesn't seem to be a Microsoft 365 Roadmap item for Application Guard for Office 365 ProPlus. However, this Microsoft document indicated it's currently at the "limited preview" stage:

Application Guard is currently in limited preview, and we're expanding the preview to include more customers. If you're interested in participating, please complete this form

Both Safe Documents and Application Guard for Office 365 ProPlus will require "Microsoft 365 E5 and E5 Security" licensing when they are commercially released, the announcement explained. The E5 plans are at the higher end of Microsoft's pricing spectrum.

Security researcher Kevin Beaumont noted in a Feb. 13 Twitter post that the Safe Documents feature "is pretty cool" but that it is "unfortunately locked behind E5 licensing."

About the Author

Kurt Mackie is senior news producer for 1105 Media's Converge360 group.


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