BigDiskBuster

BigDiskBuster Exploit Blocks Microsoft Defender Updates on All Supported Windows Versions

Security researcher Abdelhamid Naseri, known as Nightmare Eclipse, has released BigDiskBuster, a new exploit targeting Microsoft Defender that prevents the platform and antivirus signatures from receiving updates. The tool leaves Windows systems protected only by an outdated threat database while the interface continues to display normal status indicators. BigDiskBuster works across all currently supported Windows versions but requires continuous background execution. The researcher has published the source code on GitHub and acknowledged that the current implementation contains bugs requiring further refinement. The technique closely resembles the earlier UnDefend tool released in April, which similarly interfered with Defender update mechanisms. Naseri has disclosed nearly a dozen proof-of-concept exploits since April affecting Microsoft Defender, BitLocker, and other Windows components, including ShieldCrash, ShieldBreak, RoguePlanet, LegacyHive, BlueHammer, RedSun, YellowKey, and Plasma variants. Microsoft has not yet issued a patch for BigDiskBuster and previously criticized uncoordinated public disclosures of working exploits.