Microsoft releases fix for the critical Windows Defender vulnerability found by Google

As we reported yesterday, two Google security researchers recently discovered a critical bug in Windows Defender, which they described as “the worst Windows remote code exec in recent memory.” The vulnerability was indeed pretty bad, as the researchers explained that attacks could work against the default install and spread to other PCs.

Fortunately, Microsoft has just announced that a fix is now available to download on PCs running Windows 7, 8.1, RT, 10 and Windows Server 2016.

Just released malware protection engine update to
address RCE vuln – Defender will autoupdate. https://t.co/rzn5QWo6sV

— Security Response (@msftsecresponse) May 9, 2017

As the company explained, the remote code execution vulnerability could be exploited when the Microsoft Malware Protection Engine was not properly scanning specially crafted files. You can find more details below:

To exploit this vulnerability, a specially crafted file must be scanned by an affected version of the Microsoft Malware Protection Engine. There are many ways that an attacker could place a specially crafted file in a location that is scanned by the Microsoft Malware Protection Engine. For example, an attacker could use a website to deliver a specially crafted file to the victim’s system that is scanned when the website is viewed by the user. An attacker could also deliver a specially crafted file via an email message or in an Instant Messenger message that is scanned when the file is opened. In addition, an attacker could take advantage of websites that accept or host user-provided content, to upload a specially crafted file to a shared location that is scanned by the Malware Protection Engine running on the hosting server.

The company added that it had “not received any information to indicate that this vulnerability had been publicly used to attack customers,” which is reassuring. The update to the Microsoft Malware Protection Engine should be downloaded automatically on your PC, but you can install it immediately by checking Windows Update.