This article describes antimalware update package for Microsoft Defender in the OS installation images (WIM and VHD files). No ordering is required to apply the latest cumulative update (LCU) versus the Microsoft Defender update offline. A 3-month update frequency is recommended. We recommend you regularly service OS installation images to update Microsoft Defender binaries and minimize this protection gap in new deployments. Devices using either the Windows built-in antivirus or another security solution can benefit from these updates. Defender updates also contain critical performance fixes that will improve the user experience. The devices on which these deployments are made are inadequately protected until they receive the first antimalware software update. This is because the OS installation images may contain outdated antimalware software binaries. The first hours of a newly installed Windows deployment can leave the system vulnerable because of a Microsoft Defender protection gap.
