Microsoft's Digital Crimes Unit (DCU) and global partners have halted Lumma Stealer, one of cybercriminals' most common info-stealing malware tools. On May 13, Microsoft and law enforcement agencies seized nearly 2,300 domains that comprise Lumma's infrastructure, inflicting a significant blow to cybercrime networks targeting sensitive private and institutional data.
Lumma is a Malware-as-a-Service (MaaS) that has been advertised on underground forums since 2022. It specialises in siphoning passwords, banking credentials, cryptocurrency wallets, and other information. Its victims include individual consumers, schools, banks, and critical service providers. Between March and May 2025, Microsoft found about 394,000 Lumma-infected Windows systems. The majority of these systems were located in Brazil, the United States, and other parts of Europe.
The operation, which was permitted by the US District Court for the Northern District of Georgia, involved Microsoft, the US Department of Justice, Europol, and Japan's Cybercrime Control Centre. The DOJ removed Lumma's command infrastructure, while law enforcement assisted in the suspension of local networks that supported the malware.
Microsoft is sending over 1,300 confiscated or transferred domains to its "sinkholes"—a defensive infrastructure that intercepts malicious traffic in order to detect and prevent further attempts. The insights gained from these sinkholes will help public and private cybersecurity operations to investigate, track, and neutralise Lumma-related threats.
Lumma, which is designed to avoid detection, has been popular among ransomware gangs such as Octo Tempest (also known as Scattered Spider). It spreads via phishing attacks, malvertising, and impersonation frauds, such as a recent attack that used Booking.com to perpetrate financial theft.
Lumma has been used against sectors like healthcare, telecom, and logistics in addition to financial fraud, highlighting the wide-ranging and persistent threat it poses.
“We know cybercriminals are persistent and creative. We, too, must evolve to identify new ways to disrupt malicious activities. Microsoft’s DCU will continue to adapt and innovate to counteract cybercrime and help ensure the safety of critical infrastructure, customers, and online users,” noted Microsoft in a blog post.
