
Key="HKEY_LOCAL_MACHINE" Subkey="SOFTWARE\Microsoft\Windows\CurrentVersion\QualityCompat" Value="cadca5fe-87d3-4b96-b7fb-a231484277cc" Type="REG_DWORD”
The goal is for the anti-virus vendor to state they are compatible with the Spectre and Meltdown security updates and by setting this flag, they will accept these patches and allow future patches to provide compatibility. If the anti-virus vendor does not set the flag as a part of the update, then they have not proven co-existence and windows update stops working. Then, you will not receive any more updates. So here is the rub. If you are running an older anti-virus solution and have not updated it in a while or have a vendor that has still not proven compatibility and set the appropriate registry flag – you are not getting updates. Yes, you are stuck and thus vulnerable to any new exploits and cannot receive patches until they update the solution and you deploy the update – everywhere. This means you may have missed the X month patch update cycle and may miss Y month as well since your anti-virus vendor is not compatible – yet. You may even be forced to upgrade your anti-virus license or change vendors if the delay is too long in order to maintain proper security and regulatory compliance. But here is the messy part. Malware, executing with the proper privileges, could tamper with this registry key and revert to an acceptable state to stop updates in the future. This could allow a persistent presence that may be resolved with future Windows Updates. Essentially, this technique controls future Windows Updates and provides a vehicle for tampering with the entire process – something that has not been implemented before in Windows, to control when updates should stop due to incompatibility. End users and business should, therefore, take note. If machines stop receiving updates –check if your anti-virus vendor is compatible and if they have done the proper due diligence in setting the registry key. Machines that are not set are going to fall out of your patch cycle. In addition, if you use a third-party patch solution, they need to honor this setting as well. Otherwise, future updates could cause issues to the host if anti-virus is not compatible – and newer Windows Updates are applied.