Ransomware crews exploit Microsoft Defender BlueHammer privilege escalation

Intelligence Summary

CISA says ransomware operators are now using the Windows BlueHammer flaw to gain elevated privileges. The issue is tied to a Microsoft Defender privilege escalation vulnerability previously seen in zero-day activity. Exploitation can enable attackers to move from initial access to higher-impact actions on compromised systems. The risk is greater for organizations that run vulnerable Windows configurations without the relevant protections. Defenders should review CISA guidance, hunt for related activity, and ensure systems are updated and hardened.

Recommended Action

Prioritize immediate review, validate exposure, and patch or mitigate affected systems.

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