Microsoft has just issued a new warning for millions of Windows users, with “threat actors increasingly using [new] tactics aimed at circumventing defense mechanisms.” These attacks have escalated over the last six months, and the company has now issued a detailed set of recommendations.

Our dependability on the Microsoft Windows OS came under spotlight during a massive outage that was caused due to a faulty CrowdStrike update.

As spotted by Neowin, Microsoft has quietly updated its official advice for unsupported versions of Windows, which currently includes Windows 8.1, Windows 7, Windows Vista and Windows XP. These ageing operating systems no longer receive security updates from Microsoft and are therefore susceptible to attacks from hackers seeking bugs and vulnerabilities in software to access your personal and sensitive data.

At least those 900 million Windows 10 users have another year before support ends—absent a surprise Microsoft support extension, an affordable support package or a workable workaround. But for 50-million Windows users that end of support nightmare has come true, and Microsoft is warning them of the consequences.