Application Guard for Office now generally available
Published Jan 27 2021 10:00 AM 26.1K Views

With many businesses transitioning to permanent remote work, a hybrid approach, or returning to the office, organizational efforts around protecting business-critical information is crucial. Files from the internet and other potentially unsafe locations can contain viruses, worms, or other kinds of malware that can harm computers and data. To help protect your users against zero-day exploits and other advanced attacks no matter where your users work from, Office 365 opens files from potentially unsafe locations in Application Guard. To help enable you to deliver secure productivity regardless of the model your business chooses, we are pleased to announce that Application Guard for Office* is now generally available!


Stay productive while protecting against threats


Application Guard is an enterprise security feature that isolates untrusted documents in a virtualized sandbox to protect your users against malicious and potentially harmful threats. When users encounter documents from untrusted sources that aren't malicious, they can continue to be productive without worrying about putting devices, data, or identities in their organization at risk. When a user does encounter a malicious document it is safely isolated within Application Guard. Finally, every malicious attack contained by Application Guard improves our threat intelligence, which enhances our detections and ability to protect your organization and all our customers.


The user is informed when a file is opened in Application GuardThe user is informed when a file is opened in Application Guard


How Application Guard differs from Protected View 


The power of Application Guard comes from the seamless integration among Windows 10, Microsoft 365 Apps, and Microsoft Defender for Endpoint. ​ 


Application Guard differs from Protected View in that Protected View opens files in read-only mode so users can see a file’s contents and choose to enable editing. Application Guard opens files in an isolated mode that allows users to perform limited editing or printing of untrusted documents while keeping the file isolated from the rest of the device. Unlike Protected View, when Office opens files in Application Guard, users can securely read, edit, print, and save those files without having to re-open files outside the container. Application Guard uses Hyper-V-based containers, which also protects against kernel-based attacks. 


You can configure Application Guard settings for specific file types, such as Outlook attachments, text-based files (.csv, .dif, .sylk), database files (.dbf), or files originating from the internet or stored in potentially unsafe locations, such as the Temporary Internet folder on a device. 


When you enable Application Guard, the following files that used to open in Protected View will now open in Application Guard: 

  • Files originating from the internet: Any files that are downloaded from domains that are not part of either the local intranet or a Trusted Sites domain on a device, files that were received as email attachments from senders outside your organization, files that were received from other kinds of internet messaging or sharing services, or files opened from a OneDrive or SharePoint location outside your organization. 
  • Files located in potentially unsafe locations: Any folders on your computer or network that are considered unsafe, such as the Temporary Internet folder or other folders assigned by an administrator. These files open in read-only mode in Application Guard, and users can save a copy to continue working with them. 
  • Files blocked by File Block: File Block prevents outdated file types from opening, opens files in Protected View and disables the Save and Open features. Learn more about File Block. 


File opened in Application GuardFile opened in Application Guard



How Application Guard works 


When you’ve enabled Application Guard and a user opens a file from a potentially unsafe location, Office opens the file in Application Guard; a secured, Hyper-V-enabled container isolated from the rest of a user’s data through hardware-based virtualization. This container isolation means that if a document is malicious, the host PC is protected and the attacker can't access any enterprise data. For example, because the isolated container is anonymous, an attacker can't access a user’s enterprise data. If malicious content is detected in a document opened in Application Guard, tenant administrators can review these events in the Microsoft Defender for Endpoint. You can deploy Application Guard easily by changing one setting, and you can manage the feature with existing Windows tools and policies.  


If a user is confident a file is safe and needs to perform an action that is blocked by Application Guard, they can choose to remove protection from that file. Additionally, iSafe Documents is enabled, the document will be scanned before opening. 


Safeguard company data in Microsoft 365 Apps using enterprise-level security  


Application Guard works in conjunction with Microsoft Defender for Office 365,** which helps protect email and collaboration from zero-day malware, phishing, and compromise to business email. Microsoft Defender for Office 365 includes security features, such as Safe AttachmentsSafe Links, and Safe Documents to help you combat malicious activity that threatens users, devices, and data across your organization without compromising productivity. Depending on your Office 365 subscription, you can access more advanced features, such as automated post-breach investigation, hunting, and response, as well as attack simulation and end user training. 


For example, before a user can open a file in Application Guard directly on their device, Safe Documents uses Microsoft Defender for Endpoint to scan it and detect if any malicious threat exists. If it detects a threat, Safe Documents keeps the file in Application Guard, protecting devices and information 


In addition, thelp secure applications without affecting productivitySecurity Policy Advisor analyzes how individuals use Microsoft 365 Apps for enterprise and then recommends specific policies to boost your security profile. These recommendations are based on Microsoft's best practices and information about your organization’s existing environment. 


Enable Application Guard and learn more 


Application Guard will be off by default. Administrators will need to enable the feature and set the correct policy for users in their organizationTo learn more about Application Guard, review the Installation Guide and check out the User Guide on the Office Support website.   


Continue the conversation and join us in the Microsoft 365 Tech Community. Whether you have product questions or just want to stay informed with the latest updates on new releases, tools, and blogs, Microsoft 365 Tech Community is your go-to resource to stay connected! 


*At GA, Application Guard will be available to customers on Current Channel and Monthly Enterprise Channel. The feature will be available in Semi-Annual Enterprise Channel later this year. Application Guard is available to participating organizations that have Microsoft 365 E5 or Microsoft 365 E5 Security licenses.  


**Features available in Microsoft Defender for Office 365 depend on your licensing agreement. This article spells out the differences in Office 365 security, based on subscription plans. 

Version history
Last update:
‎May 11 2021 01:58 PM
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