The U.S. Federal Bureau of Investigation (FBI) Cyber Division (Internet Crime Complaint Center) has issued a warning that certain malicious cyber actors are targeting law firms. Law firms are a ripe target for valuable information concerning clients, including intellectual property. The warning states, in part:
The cyber threat actor Silent Ransom Group (SRG), also known
as Luna Moth, Chatty Spider, and UNC3753, is targeting law firms using
information technology (IT) themed social engineering calls, and callback
phishing emails, to gain remote access to systems or devices and steal
sensitive data to extort the victims. While SRG has historically victimized
companies in many sectors, starting Spring 2023, the group has consistently
targeted US-based law firms, likely due to the highly sensitive nature of legal
industry data. . . .
As of March 2025, SRG was observed changing their tactics to
calling individuals and posing as an employee from their company’s IT
department. SRG will then direct the employee to join a remote access session,
either through an email sent to them, or navigating to a web page. Once the
employee grants access to their device, they are told that work needs to be
done overnight. Once in the victim’s device, a typical SRG attack involves
minimal privilege escalation and quickly pivots to data exfiltration conducted
through “WinSCP” (Windows Secure Copy) or a hidden or renamed version of
“Rclone.” If the compromised device does not have administrative privileges,
WinSCP portable is used to exfiltrate victim data. Although this tactic has
only been observed recently, it has been highly effective and resulted in
multiple compromises. Similar to their phishing emails posing as a company with
a subscription, once SRG exfiltrates data, they extort the victim by sending
them a ransom email threatening to sell or post the data online. SRG will also
call employees at a victim company to pressure them into engaging in ransom
negotiations. SRG has developed a publicly available site to post victim data,
however, they are inconsistent in their use of the site, and do not always
follow through on posting victim data.