Google today disclosed the existence of a Windows zero-day vulnerability under attack. The flaw was reported to Microsoft 10 days ago; Microsoft says the disclosure puts users at risk.

An obscure Windows feature known as hotpatching, missing in the OS since the introduction of Windows 8, is a preferred tool used by a resourced attack group called Platinum that was uncovered by Microsoft. The group has carried out targeted attacks in South and Southeast Asia since at least 2009, focusing primarily on government interests,...