New Microsoft Defender Zero-Day Blocks Antivirus Security Updates Across Windows

A security researcher has released proof-of-concept code for a new Microsoft Defender vulnerability that can prevent the antivirus platform from installing security-intelligence and platform updates across supported versions of Windows.

The newly disclosed technique, named BigDiskBuster, targets the process Microsoft Defender Antivirus uses to stage and install updates. If successfully deployed, it can keep the security product running while quietly preventing it from receiving the latest malware signatures, detection logic, scanning-engine components and platform improvements.

The issue was disclosed by security researcher Abdelhamid Naceri, who also uses the online name Nightmare Eclipse. Naceri published the BigDiskBuster source code over the weekend and described the issue as a denial-of-service vulnerability…