Microsoft released special Defender update for Windows 11, Windows 10 install images

Microsoft had recently released new Defender anti-malware update package for Windows OS installation images, ie, for Windows Imaging Format (WIM) and VHD (Virtual Hard Disk) formats. The new definitions support Windows 11, all editions of Windows 10, Windows Servers 2016 and 2019. This update package is necessary as a Windows installation image may contain old, outdated anti-malware definitions and software binaries. Aside from better security, these updates can also provide improved performance benefits too in some cases.

Microsoft is delivering the latest security definitions for Windows images via security intelligence update version 1.385.1537.0. The Defender package version is 20230330.2. On the support document describing the the new update, Microsoft writes:

The first hours of a newly installed Windows deployment can leave the system vulnerable because of a Microsoft Defender protection gap. This is because the OS installation images may contain outdated antimalware software binaries.

[..] Devices using either the Windows built-in antivirus or another security solution can benefit from these updates.

[..] This article describes antimalware update package for Microsoft Defender in the OS installation images (WIM and VHD files). This feature supports the following OS installation images:

• Windows 11
• Windows 10 (Enterprise, Pro, and Home editions)
• Windows Server 2019
• Windows Server 2016

Version information

• Defender package version: 20230330.2

This package updates the anti-malware client, anti-malware engine, and signature versions in the OS installation images to following versions:

• Platform version: 4.18.2302.7
• Engine version: 1.1.20100.6
• Security intelligence version: 1.385.1537.0

From Microsoft’s security bulletin, we learn that the security intelligence update version 1.385.1537.0 was released at the end of last month. It adds threat detections for various trojans, hacktools, ransomware, among others. For those wondering, the latest intelligence update is version 1.387.1114.0 at the time of writing.