Security News > 2023 > March > Microsoft OneNote will block 120 dangerous file extensions
Microsoft has shared more information on what malicious embedded files OneNote will soon block to defend users against ongoing phishing attacks pushing malware.
While previously, OneNote warned users that opening attachments could harm their data but still allowed them to open the embedded files tagged as dangerous, after the security improvement rolls out, users will no longer have the choice to open files with dangerous extensions.
It will not be available in OneNote on the web, OneNote for Windows 10, OneNote on a Mac, or OneNote on Android or iOS devices.
To block additional file extensions you might consider dangerous, activate the 'Block additional file extensions for OLE embedding' policy under User ConfigurationPoliciesAdministrative TemplatesMicrosoft Office 2016Security Settings and select the extensions you want to be blocked.
On the other hand, if you need to allow specific file extensions that will soon be blocked by default, you can toggle on the 'Allow file extensions for OLE embedding' policy from the same location in the Group Policy Management Console and specify which extensions you wish to allow.
Microsoft Office group policies can also be used to restrict the launching of OneNote embedded file attachments until the new security improvements roll out.