Quote:Microsoft today announced the general availability of the Office 365 Safe Documents security feature which expands the protection provided by Protected View by checking untrusted documents for risks and known threats.

Safe Documents — launched in private preview in February — uses Microsoft Defender Advanced Threat Protection (ATP) to scan documents opened in Protected view and block users from editing them until a verdict is available.

Protected View is a read-only Office mode for opening documents deemed as potentially unsafe where most editing features are disabled to protect the users' from threats.

"Although Protected View helps secure documents originating outside the organization, people too often exit the protection sandbox without considering if the document is safe – leaving their organizations vulnerable," Microsoft said.
"To improve this trust promotion experience for Microsoft 365 Apps, Safe Documents takes away the guesswork by automatically verifying the document against the latest known risks and threat profiles before allowing users to leave the Protected View container."

Safe Documents in action (Microsoft)