Silent Ransom Group Targets US Legal Firms With Voice Phishing and Data Theft Extortion

**Executive summary:** Mandiant and Google identify UNC3753 (Luna Moth/Chatty Spider/Silent Ransom Group) conducting fast, human-focused data-theft extortion against U.S. legal, financial, and professional services firms by combining vishing, social engineering, abuse of legitimate screen-sharing/RMM tools, and occasional physical access to quickly locate and exfiltrate high-value legal and PII data for rapid extortion demands; the report includes attack lifecycle details, pragmatic exfiltration methods, observed IOCs, and recommended mitigations.