BigDiskBuster: New Vulnerability Blocks Antivirus Updates Across Windows Versions

A new vulnerability in Microsoft Defender has been disclosed by security researcher Abdelhamid Naceri. The technique, named BigDiskBuster, targets the process Microsoft Defender Antivirus uses to stage and install updates.

The proof-of-concept code works on all currently supported Windows versions and can prevent Defender from receiving the latest malware signatures, detection logic, scanning-engine components, and platform improvements.

Naceri published the BigDiskBuster source code over the weekend, describing the issue as a denial-of-service vulnerability affecting Defender’s update mechanism. At the time of publication, Microsoft had not publicly confirmed the vulnerability or released a security update specifically addressing BigDiskBuster.