Attackers can exploit the vulnerability to compromise Windows systems running affected Microsoft security products, including Windows Defender and Microsoft Security Essentials.
Microsoft has released an update for the malware scanning engine bundled with most of its Windows security products in order to fix a highly critical vulnerability that could allow attackers to hack computers.
The vulnerability was discovered by Google Project Zero researchers Tavis Ormandy and Natalie Silvanovich on Saturday and was serious enough for Microsoft to create and release a patch by Monday. This was an unusually fast response for the company, which typically releases security updates on the second Tuesday of every month and rarely breaks out of that cycle.
According to a Microsoft security advisory published Monday, the vulnerability can be triggered when the Microsoft Malware Protection Engine scans a specially crafted file. The engine is used by Windows Defender, the malware scanner preinstalled on Windows 7 and later, as well as by other Microsoft consumer and enterprise security products: Microsoft Security Essentials, Microsoft Forefront Endpoint Protection 2010, Microsoft Endpoint Protection, Microsoft Forefront Security for SharePoint Service Pack 3, Microsoft System Center Endpoint Protection and Windows Intune Endpoint Protection.
Administrators of enterprise antimalware deployments should ensure that their update management software is configured to automatically approve and distribute engine updates and new malware definitions,” Microsoft said in its advisory. “Enterprise administrators should also verify that the latest version of the Microsoft Malware Protection Engine and definition updates are being actively downloaded, approved and deployed in their environment.