Quote:Microsoft today announced the launch of Application Guard for Office in public preview to protect enterprise users from threats using malicious attachments as an attack vector.
 
Application Guard for Office (also known as Microsoft Defender Application Guard for Office) is designed to help prevent block files downloaded from untrusted sources from gaining access trusted resources by opening them within an isolated sandbox.
 
This sandbox will automatically block maliciously crafted files from exploiting vulnerabilities, downloading other malicious tools, or manifesting any malicious behavior from impacting the users' device and data.
 
Application Guard for Office was initially launched in limited preview last year, in November 2019.

"To help protect your users, Office opens files from potentially unsafe locations in Application Guard, a secure container that is isolated from the device through hardware-based virtualization," Microsoft Sr. Office Deployment Engineer Eric Wayne said. "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."
 

Alert shown when opening untrusted files in Office (Microsoft)