Intel asking everyone to skip its flawed firmware updates was apparently not enough for Microsoft. Over the weekend, the Redmond giant released another emergency update for Windows 7, Windows 8.1, and Windows 10 that disable Intel’s mitigation against Spectre variant 2, which has been causing system instability (via The Verge).
Intel previously acknowledged that recent security patches for all processors released over the last five years could cause reboot issues. “Our own experience is that system instability can in some circumstances cause data loss or corruption,” Microsoft added in a support page this weekend.
The chip maker also said that it has already identified the root cause of reboot issues on Broadwell and Haswell processors, and that it's currently working on new firmware updates for these CPU architectures. Obviously, Microsoft didn't want to wait as these system instability are more serious than expected:
While Intel tests, updates and deploys new microcode, we are making available an out of band update today, KB4078130, that specifically disables only the mitigation against CVE-2017-5715 – “Branch target injection vulnerability.” In our testing this update has been found to prevent the behavior described.
For now, the KB4078130 security update is only available to download from the Microsoft Update Catalog website. IT admins can also manually disable Intel’s mitigation against Spectre Variant 2 by applying new registry key settings, and more details are available on this support page.
"As of January 25, there are no known reports to indicate that this Spectre variant 2 (CVE 2017-5715 ) has been used to attack customers," Microsoft added. Installing this new Windows update will leave your PC unprotected against this Spectre variant, though you may not really have a choice if you did encounter reboot issues (or worse) after installing recent firmware updates from Intel.