Cybersecurity researchers have uncovered a new technique where attackers use fake Captcha tests to trick people into installing malware called Lumma Stealer. This malicious program is designed to quietly search infected computers for valuable information, such as login credentials, cryptocurrency wallet details, and two-factor authentication codes.
The scheme first appeared on a Greek banking website, where users were shown what looked like a Captcha security test. Instead of a normal verification, the prompt instructed Windows users to copy a piece of text into their Run dialog box and press Enter. By doing so, victims unknowingly triggered the installation of Lumma Stealer without downloading a visible file.
According to data shared by DNSFilter, a security company monitoring the incident, clients came across this fake Captcha 23 times in just three days. Alarmingly, around 17% of users who saw it followed the instructions, which led to attempts to infect their systems with malware.
How Lumma Stealer Works
Once inside a computer, Lumma Stealer immediately begins searching for anything that can be exploited for profit. This includes saved browser passwords, cookies, stored two-factor authentication tokens, cryptocurrency wallets, and even the data kept in password managers. Cybercriminals can use this stolen information to commit identity theft, break into financial accounts, or steal digital assets such as crypto funds.
What makes this threat particularly concerning is that Lumma Stealer can be hidden on otherwise legitimate websites, meaning unsuspecting users may fall victim even without visiting suspicious or obviously harmful pages.
Malware-as-a-Service Model
Lumma Stealer is part of a growing cybercrime trend known as Malware-as-a-Service (MaaS). Under this model, professional malware developers create the malicious software, improve its ability to avoid detection, and maintain hosting services. They then rent access to the malware to other cybercriminals in exchange for subscription fees. This arrangement makes it easy for attackers with little technical expertise to launch damaging campaigns.
Earlier this year, authorities attempted to disrupt Lumma Stealer operations. The U.S. Department of Justice seized several domains linked to the malware, while Microsoft removed thousands of related websites. However, security analysts report that Lumma Stealer quickly resurfaced, showing just how resilient and profitable such services can be.
Part of Lumma Stealer’s popularity comes from its low cost. Subscriptions can be found on underground forums for only a few hundred dollars per month, yet the potential financial return for criminals is enormous. In recent analyses, experts estimated that hundreds of thousands of devices have been compromised, with losses reaching tens of millions of dollars.
The importance of staying alert online cannot be emphasised enough. Unusual instructions, such as copying text into a computer’s Run command should raise suspicion immediately. Cybersecurity specialists advise users to verify unexpected prompts and ensure their systems are protected with updated security tools to reduce the risk of infection.
