clickfix

Once-hobbled Lumma Stealer is back with lures that are hard to resist

Last May, law enforcement authorities around the world scored a key win when they hobbled the infrastructure of Lumma, an infostealer that infected nearly 395,000 Windows computers over just a two-month span leading up to the international operation. Researchers said Wednesday that Lumma is once again “back at scale” in hard-to-detect attacks that pilfer credentials and sensitive files.

Lumma, also known as Lumma Stealer, first appeared in Russian-speaking cybercrime forums in 2022. Its cloud-based malware-as-a-service model provided a sprawling infrastructure of domains for hosting lure sites offering free cracked software, games, and pirated movies, as well as command-and-control channels and everything else a threat actor needed to run their infostealing enterprise. Within a year, Lumma was selling for as much as $2,500 for premium versions. By the spring of 2024, the FBI counted more than 21,000 listings on crime forums. Last year, Microsoft said Lumma had become the “go-to tool” for multiple crime groups, including Scattered Spider, one of the most prolific groups.

Takedowns are hard

The FBI and an international coalition of its counterparts took action early last year. In May, they said they seized 2,300 domains, command-and-control infrastructure, and crime marketplaces that had enabled the infostealer to thrive. Recently, however, the malware has made a comeback, allowing it to infect a significant number of machines again.

“LummaStealer is back at scale, despite a major 2025 law-enforcement takedown that disrupted thousands of its command-and-control domains,” researchers from security firm Bitdefender wrote. “The operation has rapidly rebuilt its infrastructure and continues to spread worldwide.”

As with Lumma before, the recent surge leans heavily on “ClickFix,” a form of social engineering lure that’s proving to be vexingly effective in causing end users to infect their own machines. Typically, these types of bait come in the form of fake CAPTCHAs that—rather requiring users to click a box or identify objects or letters in a jumbled image—instruct them to copy text and paste it into an interface, a process that takes just seconds. The text comes in the form of malicious commands provided by the fake CAPTCHA. The interface is the Windows terminal. Targets who comply then install loader malware, which in turn installs Lumma.

ClickFix may be the biggest security threat your family has never heard of

Biz & IT, clickfix, malware, Scams, Security / Rejus Almole / November 11, 2025

Another campaign, documented by Sekoia, targeted Windows users. The attackers behind it first compromise a hotel’s account for Booking.com or another online travel service. Using the information stored in the compromised accounts, the attackers contact people with pending reservations, an ability that builds immediate trust with many targets, who are eager to comply with instructions, lest their stay be canceled.

The site eventually presents a fake CAPTCHA notification that bears an almost identical look and feel to those required by content delivery network Cloudflare. The proof the notification requires for confirmation that there’s a human behind the keyboard is to copy a string of text and paste it into the Windows terminal. With that, the machine is infected with malware tracked as PureRAT.

Push Security, meanwhile, reported a ClickFix campaign with a page “adapting to the device that you’re visiting from.” Depending on the OS, the page will deliver payloads for Windows or macOS. Many of these payloads, Microsoft said, are LOLbins, the name for binaries that use a technique known as living off the land. These scripts rely solely on native capabilities built into the operating system. With no malicious files being written to disk, endpoint protection is further hamstrung.

The commands, which are often base-64 encoded to make them unreadable to humans, are often copied inside the browser sandbox, a part of most browsers that accesses the Internet in an isolated environment designed to protect devices from malware or harmful scripts. Many security tools are unable to observe and flag these actions as potentially malicious.

The attacks can also be effective given the lack of awareness. Many people have learned over the years to be suspicious of links in emails or messengers. In many users’ minds, the precaution doesn’t extend to sites that instruct them to copy a piece of text and paste it into an unfamiliar window. When the instructions come in emails from a known hotel or at the top of Google results, targets can be further caught off guard.

With many families gathering in the coming weeks for various holiday dinners, ClickFix scams are worth mentioning to those family members who ask for security advice. Microsoft Defender and other endpoint protection programs offer some defenses against these attacks, but they can, in some cases, be bypassed. That means that, for now, awareness is the best countermeasure.

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