As cybercriminals sharpen their social engineering techniques, a new attack method is gaining momentum — and it’s catching even the cautious off guard. In a recent article published by Malware Bytes, security researcher Pieter Arntz detailed an emerging threat: fake CAPTCHA websites that hijack users’ clipboards to deploy malware, including sophisticated information stealers.
This threat may appear deceptively simple at first glance, but its implications for professionals in sensitive sectors—particularly banking—are significant. Here’s what you need to know and how to protect yourself and your institution.
How Fake CAPTCHAs Trick Bankers into Installing Malware
The attack begins in an all-too-familiar setting: a website offering access to enticing content — movies, music, photos, or news—that requests users to complete a CAPTCHA to proceed. Most visitors don’t think twice about clicking a checkbox labeled “I’m not a robot.” But this checkbox is a decoy.
Once clicked, users are prompted to complete three additional steps that seem part of the verification process:
- Press and hold the Windows key + R to open the Run dialog box.
- Paste (using Ctrl + V) whatever is in your clipboard.
- Press Enter to complete the “verification.”
What’s not made clear is that the website already uses JavaScript to silently copy a malicious command to the clipboard. By pasting and executing it, the user is unknowingly installing malware on their own system — a textbook example of “bring-your-own-malware.”
How the Banking Malware Works
The command copied to the clipboard typically calls mshta.exe, a legitimate Windows utility used to execute HTML applications. In this attack, it fetches a seemingly benign media file—an .mp3, .jpg, or .html—from a malicious domain. These files are, in reality, obfuscated PowerShell scripts.
When executed, the script runs invisibly in the background and downloads the actual payload: usually an information stealer such as Lumma Stealer or SecTopRAT. These tools are designed to:
- Capture saved credentials and browser data
- Record keystrokes and clipboard activity
- Extract sensitive information, including crypto wallets
- Upload this data to remote attacker-controlled servers
For financial professionals with privileged access to confidential client and company data, such malware presents a significant risk of data exfiltration, identity theft, and institutional compromise.
“I’m Not a Robot” CAPTCHA Deception Targeting Bankers
The insidious nature of this new bank scam involving fake CAPTCHAs relies on the target’s own actions. Victims are not infected automatically—they infect themselves by following what appear to be harmless, even routine instructions.
Moreover, these instructions are cloaked in an air of legitimacy. The command the user is tricked into pasting ends with something like:
“I’m not a robot – reCAPTCHA Verification ID: 8253”
This is not part of the command itself; it’s a comment, included at the end of the malicious line to disguise its true purpose. Many users, even experienced ones, may glance at this line and believe it’s a benign verification string.
Widespread Risk for Banking Staff
While the early use cases of this technique focused on infiltrating specific organizations, it has since broadened in scope. Today, anyone—including frontline banking staff, executives, and advisors—could be exposed. The professional banking community must recognize that:
- Phishing and malware delivery no longer rely solely on email. Web-based social engineering is now equally dangerous.
- Clipboard-based execution leverages tools that users often trust, like Windows utilities, and disguises commands as user inputs.
- Even brief lapses in caution can result in credential theft, regulatory exposure, and reputational harm for institutions.
Protecting Your Bank: A Multilayered Approach to Fake CAPTCHA Attacks
To stay ahead of this evolving threat, Arntz recommends a multilayered approach:
- Think Before You Paste: Never follow instructions from a website that asks you to open system utilities (like Run) or paste unknown content. If anything seems unusual, pause and investigate
- Use Modern Anti-Malware Tools: Ensure your bank has endpoint protection that actively scans for malicious scripts and blocks suspicious behavior. Solutions that incorporate behavioral analysis and real-time threat intelligence are ideal
- Browser Extensions Matter: Check that the bank’s IT department has installed reputable browser extensions that block access to malicious domains and prevent clipboard manipulation, such as uBlock Origin or NoScript
- Segregate Browser Use: Consider recommending that bank employees use different browsers for different purposes—for example, Chrome for banking portals and secure transactions, and Firefox or Brave for research or general browsing with JavaScript disabled
Ensuring that all bank employees comply with internal guidelines for online use is always recommended.
Understanding Evolving Cyber Threats in Banking
The simplicity of this attack belies its sophistication, and the consequences for the banking industry could be severe. As financial professionals entrusted with sensitive data, it’s crucial to stay informed, skeptical of unfamiliar prompts, and proactive in adopting security best practices.
This issue isn’t just about malware. It’s about recognizing when a familiar digital interaction has been weaponized—and knowing what to do when it has.
For the complete details on this issue, see the original article at Malware Bytes.
