Those of you who are using the common methods for blocking Windows 7 and Windows 8.1's obnoxious Win10 upgrade procedure take note. Apparently an update released yesterday changed an important registry setting -- DisableOSUpgrade -- that prevented Windows 7 and 8.1 from proceeding with the forced march to Windows 10.
If you've used GWX Control Panel, gpedit/Computer Configuration, and/or direct changes to the registry to block the Windows 10 upgrade, you should take a moment and make sure that your block is still in place.
For most of you, that's as easy as re-running GWX Control Panel and clicking "Disable Operating System Upgrades in Windows Update." If you're using Group Policy, follow the directions in Microsoft's KB 3080351 to "Turn off the upgrade to the latest version of Windows through Windows Update." If you're setting the registry manually, make sure the following key has a Dword value of DisableOSUpgrade = 1.
Why the alarm? Late last night, GWX Control Panel author Josh Mayfield sent me an email:
Just came home this evening to find three of my Windows 7 computers had reverted to "Windows Update OS upgrades enabled" mode in GWX Control Panel. This means that Windows either changed or deleted registry settings that GWX Control Panel had earlier put in place... and I THINK I found the culprit: One of the updates that these computers installed today is KB3083710, which is a client update for Windows Update itself. It may be that Microsoft wasn't intentionally/explicitly wiping out settings related to the Win 10 download, and really they were just wiping ALL Windows Update settings as part of this patch.
It's possible that KB 3083710 (for Windows 7) or KB 3083711 (for Windows 8.1) wiped out that registry setting.
On some PCs, KB 3083710 and KB 3083711 were changed on Tuesday, with their status going from optional-and-unchecked to important-and-checked. That may account for the registry change on Wednesday (Windows Update changes to the registry only "take" upon restart).
Tell your friends and warn your neighbors. If you don't want to upgrade to Windows 10 right now, run GWX Control Panel today, and run it again every time Microsoft makes changes to your Windows 7 or 8.1 PC.
Key question: At what point does a potentially unwanted program become malware?
Follow-up question: Why don't antivirus products scan for GWX?