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Researcher Drops BigDiskBuster Zero-Day PoC That Blocks Microsoft Defender Updates

thehackernews.com 2026-09-22 AI agent abuse High

What Happened

A zero-day proof-of-concept tool that stops Microsoft Defender from installing platform and signature updates by filling all available disk space was published on GitHub on September 19. The tool, called BigDiskBuster, has no patch, no CVE, and no Microsoft advisory. Its author, Abdelhamid Naceri, is a former Microsoft security researcher whose earlier Defender exploits were used in

Why It Matters

The report describes BigDiskBuster, a proof-of-concept that fills available disk space to prevent Microsoft Defender platform and signature updates, leaving detection content stale. It does not involve artificial intelligence systems, AI agents, models, training data, or AI-enabled services. The AI classification is therefore only a forced fallback; RealGround services have no direct applicability to this endpoint-security issue.

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RealGround Analysis

This signal maps to AI agent abuse. Organizations using AI agents, LLM APIs, SaaS integrations, or sensitive data workflows should review whether this class of issue could create unauthorized tool execution, data leakage, weak approval gates, or unmanaged supply-chain exposure.

Recommended Actions

  • Restrict AI agent tool permissions and production write paths.
  • Review sensitive data access across prompts, logs, embeddings, memory, and SaaS integrations.
  • Add human approval workflows for high-impact or state-changing actions.
  • Run prompt injection and indirect prompt injection tests against affected workflows.
  • Document the owner, control gap, and remediation deadline for this risk class.

Source

https://thehackernews.com/2026/09/researcher-drops-bigdiskbuster-zero-day.html

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