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  • Will Hughes

Beware of new Office 365 Security Vulnerability

A new “Zero Day” critical severity security vulnerability is now being actively exploited by hackers to attack computers and servers running Office 365 applications, it has been formally identified as CVE-2021-40444.

IT Support Office 365 Vulnerability

Microsoft have stated that they are "investigating reports of a remote code execution vulnerability in MSHTML that affects Microsoft Windows. Microsoft is aware of targeted attacks that attempt to exploit this vulnerability by using specially-crafted Microsoft Office documents.

An attacker could craft a malicious ActiveX control to be used by a Microsoft Office document that hosts the browser rendering engine. The attacker would then have to convince the user to open the malicious document.”

In layman’s terms – a document specially crafted by a hacker, if opened, would allow the hacker to run code on your computer. This could allow them to take control of the computer or infect it with ransomware for the purposes of extorting you or your business.

We have already started rolling out mitigations to our IT Support and Managed Services customers. We strongly suggest your business also enacts mitigations against this vulnerability.

EDIT: A full security update for this vulnerability has now been released. Further information and patch details can be found here: CVE-2021-40444 - Security Update Guide - Microsoft - Microsoft MSHTML Remote Code Execution Vulnerability

If your business requires assistance with protecting against this critical security vulnerability, please do not hesitate to get in touch with us.


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