Zero-Day Flaw in Microsoft Defender Leveraged by Attackers
SecurityWeek reports a critical zero-day vulnerability in Microsoft Defender has been actively exploited. This flaw grants attackers the ability to access the Security Account Manager (SAM) database. From there, they can extract NTLM hashes, a key step in credential theft and lateral movement. Ultimately, this allows adversaries to escalate privileges to the highest level, gaining full control of affected systems.
This exploit bypasses the very product intended to protect endpoints, highlighting a significant blind spot for defenders. The fact that it’s a zero-day means organizations likely had no prior warning and no specific defenses in place before exploitation began. Attackers are prioritizing this vulnerability for its direct path to high-level system compromise.
What This Means For You
- If your organization relies on Microsoft Defender for endpoint protection, investigate immediate patching or mitigation steps for this specific vulnerability. Audit your SAM database access logs and look for any unusual NTLM hash extraction attempts or privilege escalation events.
Related ATT&CK Techniques
🛡️ Detection Rules
3 rules · 6 SIEM formats3 detection rules auto-generated for this incident, mapped to MITRE ATT&CK. Sigma YAML is free — export to any SIEM format via the Intel Bot.
Zero-Day Microsoft Defender SAM Access - Free Tier
Indicators of Compromise
| ID | Type | Indicator |
|---|---|---|
| Microsoft-Defender-Zero-Day | Privilege Escalation | Microsoft Defender |
| Microsoft-Defender-Zero-Day | Information Disclosure | Access to SAM database |
| Microsoft-Defender-Zero-Day | Information Disclosure | Extraction of NTLM hashes |
Written by SCW Vulnerability Desk
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