This past week Microsoft released the Patch Tuesday updates for August 2025 on Windows 10 (KB5063709 / KB5063877 / KB5063871 / KB5063889) and for Windows 11 (KB5063878, KB5063875).
Aside from that, Microsoft also published a new Defender update for Windows 11/10/Server installation images. This update package is necessary as a Windows installation image may contain old, outdated anti-malware definitions and software binaries.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 in some cases.
When a new Windows installation is set up, there may be a temporary security risk due to outdated Microsoft Defender protection in the OS installation images. This happens because the antimalware software included in these images might not be up to date. Thus Microsoft says that these updated definitions essentially help close this protection gap.
Microsoft delivered the latest security definitions for Windows images via security intelligence update version 1.431.796.0. The Defender package version is also the same.
It applies to Windows 11, Windows 10 (Enterprise, Pro, and Home editions), Windows Server 2022, Windows Server 2019, and Windows Server 2016. Microsoft writes:
Version information
• Defender package version: 1.431.796.0
This package updates the anti-malware client, anti-malware engine, and signature versions in the OS installation images to following versions:
• Platform version: 4.18.25070.5
• Engine version: 1.1.25070.4
• Security intelligence version: 1.431.796.0
From Microsoft's security bulletin, we learn that the security intelligence update version 1.431.796.0 was released towards the end of last month and adds threat detections for various stealer malware including Lumma, which affected nearly 400,000 systems across the world. Microsoft had already released an earlier Defender update for that, but it looks like some of it was still out there undetected.
You can find more information about it in this article on Microsoft's official website. For those wondering, the latest intelligence update is version 1.435.225.0 at the time of writing.
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