The advisory was posted on the Microsoft Security Response Center’s (MSRC) website, which is Mircosoft’s cybersecurity team that strives to protect users from threat actors and attacks. The vulnerability has been dubbed CVE-2021-40444, and it’s being described as a hole in MSHTML, which is the browser engine behind Internet Explorer. What threat actors do is create a Microsoft Office document that houses a malicious ActiveX control. ActiveX controls are small bits of software that allow websites to provide content on Internet Explorer. Once a user opens the infected document, the malicious ActiveX control implants malware onto the targeted computer. The MSRC currently is investigating the situation. The vulnerability has yet to be patched, although Microsoft is most likely working on fixing this problem. The issue is so severe that even the US-CERT (United States Computer Emergency Readiness Team) posted a warning on its official Twitter account for IT professionals across the country to protect their systems. Mitigations are already in place as Microsoft Office opens documents taken from the internet in Protected View or Application Guard for Office to prevent attacks. The company’s antivirus tools, like Defender for Endpoint, also can detect the exploit and protect your computer. The MSRC recommends that users keep their antivirus and anti-malware software up to date. Users who automatically update their protections have nothing to worry about.
