As part of the phased mitigation strategy we outlined on the MSRC blog, an update was released with Security Advisory 2718704 that prevents unauthorized certificates from being used to attack Windows systems. In an effort to provide additional protection for customers, the next action in our mitigation strategy is to further harden Windows Update as a defense-in-depth precaution. Now that we have seen broad adoption of Security Advisory 2718704, our deployment of the security hardening update to Windows Update and Windows Server Update Services (WSUS) infrastructures will begin to roll out over the next few days.
Our hardening introduces two defense-in-depth changes. First, we have further hardened the Windows Update infrastructure so that the Windows Update client will only trust files signed by a new certificate that is used solely to protect updates to the Windows Update client. Second, we are strengthening the communication channel used by Windows Update in a similar way. Details on the changes to the Windows Update client can be found at KB 949104. WSUS customers will also receive an update; more details can be found at KB 2720211.
As with past updates, this update will not change your current Windows Update or Automatic Updates settings. Anytime Windows Update (or Automatic Updates) is turned on, either set to automatically install updates or notify to install updates, Windows Update will take care of updating itself.
It’s important to keep your PC up to date with the latest updates to keep your PC running smoothly and safely.