As cybercrime is ever on the rise, Microsoft has declared that it will tighten the security around its OneNote application. Microsoft will block 120 file extensions that the company has identified as malicious ones.
The security updates will be implemented for OneNote apps on Windows systems by the end of April and May this year. The updates will be rolled out with version 2304 for Microsoft Office 365. This security update will also be available for the latest versions of Office 2021, Office 2019, and Office 2016 (Current Channel) exempting the bulk-licensed versions of Office. The security update also won’t be available for OneNote on the web, Windows 10, Mac, Android, and iOS devices.
This action is being taken by Microsoft when several phishing attacks have come to light since December 2022. Also, the company is eager to align the security provisions of all its applications and is hence blocking extensions for OneNote which are also blocked for Microsoft Word, Excel, Outlook, and PowerPoint.
The 120 extensions to be blocked as per the support document will be:

Earlier Microsoft was only issuing caution for users when they were about to open any suspicious file extension; however, users were still able to open embedded files. But now users will see a warning dialog such as “Your admin blocked this file type.”
Therefore, to open these blocked file extensions now, users will need to save the file on their local device and then proceed to open it.
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