Microsoft, the Department of Justice and others have thwarted the use of the Lumma Stealer malware that globally has infected nearly 400,000 computers.

Microsoft said Wednesday that it broke down the Lumma Stealer malware project with the help of law enforcement officials across the globe.

Between March 16 and May 16, 2025, Microsoft tracked over 394,000 Windows computers infected with Lumma Stealer. In response, authorities seized about 2,300 malicious domains. These domains were critical to the malware’s command-and-control infrastructure. Taking them down cut off communication between infected systems and Lumma’s operators.