Microsoft to Block Dangerous Extensions in OneNote to Prevent Malware Delivery

OneNote, Microsoft’s digital note-taking app, has become a more secure platform with the recent release of a new update that automatically blocks 120 risky file extensions. This move comes as part of Microsoft’s continuous efforts to beef up security features in its products and to protect users against potential malware infections. The decision to tighten OneNote’s security could be seen as a response to the growing cybersecurity threat landscape, which has seen an increase in cyberattacks on various industries in recent years. In this article, we’ll delve deeper into the significance of this update and how it can help users keep their digital notes safe from potential threats.


Microsoft has announced its plan to automatically block embedded files with dangerous extensions in OneNote. This comes after reports of increased malware delivery through the note-taking service. Previously, users were shown a warning when opening such attachments, but could dismiss the prompt and open the files. Going forward, Microsoft intends to prevent users from opening embedded files with dangerous extensions directly, and instead display the message: “Your administrator has blocked your ability to open this file type in OneNote.” The update will start rolling out with Version 2304 later this month and only affects OneNote for Microsoft 365 on Windows devices. Other platforms such as macOS, Android, and iOS as well as OneNote versions available on the web and for Windows 10 are not affected. Users can still open embedded files by saving them locally to their device and opening them from there. The move comes after increased use of OneNote attachments to deliver malware via phishing scams. Trellix reports a gradual increase in malicious OneNote samples since December 2022, ramping up in February 2023.


In conclusion, Microsoft’s update to OneNote is a significant step forward in ensuring the security of users’ data. By auto-blocking 120 risky file extensions, OneNote is now better equipped to protect against potential security threats, including malicious files and viruses. This security update proves Microsoft’s commitment to providing users with a secure and reliable experience with their products. As one of the most widely used note-taking apps, OneNote’s efforts to enhance security measures are crucial to safeguarding user data. By staying ahead of potential threats, Microsoft has shown that they prioritize the security and privacy of their users. As such, users can feel confident in using OneNote to its full potential without having to worry about their data being compromised.