Security News > 2023 > April > Microsoft Tightens OneNote Security by Auto-Blocking 120 Risky File Extensions

Microsoft has announced plans to automatically block embedded files with "Dangerous extensions" in OneNote following reports that the note-taking service is being increasingly abused for malware delivery.

Microsoft said it intends to prevent users from directly opening an embedded file with a dangerous extension and display the message: "Your administrator has blocked your ability to open this file type in OneNote."

The update is expected to start rolling out with Version 2304 later this month and only impacts OneNote for Microsoft 365 on devices running Windows.

"By default, OneNote blocks the same extensions that Outlook, Word, Excel, and PowerPoint do," Microsoft said.

Users who opt to still open the embedded file can do so by first saving the file locally to their device and then opening it from there.

The development comes as Microsoft's decision to block macros by default in Office files downloaded from the internet spurred threat actors to switch to OneNote attachments to deliver malware via phishing attacks.

News URL

https://thehackernews.com/2023/04/microsoft-tightens-onenote-security-by.html