This article describes antimalware update package for Microsoft Defender in the OS installation images (WIM and VHD files). Devices using either the Windows built-in antivirus or another security solution can benefit from these updates. This is because the OS installation images may contain outdated antimalware software binaries.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. There is an accompanying support document where Microsoft explains the update: There is also a Defender update that is rolling out in version 20230503.1.

Microsoft is rolling out the new definitions for Windows OS installation images through security intelligence update version 1.389.44.0. New Updated Definitions for Windows 11/10 OS Images Therefore, it is important to scan and protect offline Windows images before using them.

Malware can modify the offline Windows image files and compromise the security of the installed or repaired Windows system. However, offline Windows images can also be vulnerable to malware infections, especially if they are stored on removable media or network shares. Offline Windows images can be useful for deploying Windows to multiple devices, recovering from system errors, or customizing Windows features. Users can create offline Windows images using tools like DISM (Deployment Image Servicing and Management) or Windows PE (Windows Preinstallation Environment). Microsoft points out that the updates will make Windows installation images more secure while also increasing performance.Īn offline Windows image is a file that contains the operating system files and settings that are used to install or repair Windows. Microsoft explains the update package is needed as Windows OS installation images may have outdated definitions to protect against malware. Specifically, Microsoft Defender adds a new anti-malware update package for the installation of Windows images on Virtual Hard Disk (VHD) and Windows Imaging Format (WIM).Īccording to the company, the new definitions cover Windows 11, Windows 10, and Windows Server 20. Microsoft has released a special update for its Defender antivirus software that allows users to scan and protect their Windows 11 and Windows 10 installation images.

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