In a sweeping international crackdown earlier this month, a collaborative operation involving major tech firms and law enforcement agencies significantly disrupted the Lumma malware-as-a-service (MaaS) operation. This effort resulted in the seizure of thousands of domains and dismantling of key components of Lumma's infrastructure across the globe.
A major milestone in the operation occurred on May 13, 2025, when Microsoft, through legal action, successfully took control of around 2,300 domains associated with the malware. Simultaneously, the U.S. Department of Justice (DOJ) dismantled online marketplaces used by cybercriminals to rent Lumma’s services, while Europol’s European Cybercrime Center (EC3) and Japan’s Cybercrime Control Center (JC3) helped take down Lumma’s infrastructure in their respective regions.
"Between March 16, 2025, and May 16, 2025, Microsoft identified over 394,000 Windows computers globally infected by the Lumma malware. Working with law enforcement and industry partners, we have severed communications between the malicious tool and victims," said Steven Masada, Assistant General Counsel of Microsoft's Digital Crimes Unit.
Cloudflare, one of the key players in the effort, highlighted the impact of the takedown.
“The Lumma Stealer disruption effort denies the Lumma operators access to their control panel, marketplace of stolen data, and the Internet infrastructure used to facilitate the collection and management of that data. These actions impose operational and financial costs on both the Lumma operators and their customers, forcing them to rebuild their services on alternative infrastructure,” Cloudflare stated.
The operation saw contributions from companies like ESET, CleanDNS, Bitsight, Lumen, GMO Registry, and law firm Orrick. According to Cloudflare, the Lumma malware misused their platform to mask server IP addresses that were used to siphon off stolen credentials and sensitive data.
Even after suspending malicious domains, the malware managed to bypass Cloudflare’s interstitial warning page, prompting the company to reinforce its security measures.
"Cloudflare's Trust and Safety team repeatedly flagged domains used by the criminals and suspended their accounts," the company explained.
“In February 2025, Lumma’s malware was observed bypassing Cloudflare’s interstitial warning page, which is one countermeasure that Cloudflare employs to disrupt malicious actors. In response, Cloudflare added the Turnstile service to the interstitial warning page, so the malware could not bypass it."
Also known as LummaC2, Lumma is a sophisticated information-stealing malware offered as a subscription-based service, ranging from $250 to $1,000. It targets both Windows and macOS systems, enabling cybercriminals to exfiltrate data from browsers and apps.
Once installed, Lumma can extract a broad range of data, including login credentials, credit card numbers, cryptocurrency wallets, cookies, and browsing history from popular browsers like Google Chrome, Microsoft Edge, Mozilla Firefox, and other Chromium-based platforms. The stolen data is packaged and sent to attacker-controlled servers, where it is either sold on dark web marketplaces or used in follow-up cyberattacks.
Initially spotted in December 2022 on cybercrime forums, the malware quickly gained traction. Cybersecurity firm KELA reported its rapid rise in popularity among cybercriminals.
IBM X-Force’s 2025 threat intelligence report revealed a 12% year-on-year increase in the number of stolen credentials being sold online, largely driven by the use of infostealers like Lumma. Phishing campaigns delivering such malware have surged by 84%, making Lumma the most dominant player in this threat landscape.
Lumma has been linked to major malvertising campaigns affecting hundreds of thousands of users and has been used by notorious groups such as the Scattered Spider cybercrime collective.
Recently, stolen data linked to Lumma has played a role in high-profile breaches at companies like PowerSchool, HotTopic, CircleCI, and Snowflake. In some cases, infostealer malware has been used to manipulate internet infrastructure, such as the Orange Spain RIPE account hijacking incident that disrupted BGP and RPKI configurations.
On the day of the crackdown, the FBI and CISA jointly issued a security advisory outlining indicators of compromise (IOCs) and detailing the tactics, techniques, and procedures (TTPs) employed by threat actors using Lumma malware.
