Beware of Fake CAPTCHA

CAPTCHA prompts have become a familiar sight online. CAPTCHA prompts are designed to differentiate human users from automated bots, keeping websites secure. Unfortunately, cybercriminals are now using fake CAPTCHAs as a new vector for attacks. Recently, organizations have experienced incidents involving malicious CAPTCHAs that trick users into unintentionally running harmful commands on their computers. Here is what you need to know to stay safe.

Um, the user did what?

A recent WatchPoint security incident involved a sophisticated form of attack using deceptive CAPTCHA prompts. In this type of attack, a fake CAPTCHA asks users to complete unusual steps—like opening a Windows command prompt or running a PowerShell command—actions a legitimate CAPTCHA would never require. When users follow these malicious instructions, they unknowingly execute scripts that install malware, steal sensitive information, or gain remote access to their computers.

SentinelOne, WatchPoint's MDR platform, caught and isolated the attack immediately. Less sophisticated AV may not detect this as malicious behavior as there are no files immediately dropped classifying this type of attack as fileless.

Specifically, these fake CAPTCHAs typically instruct users to:

• Press the Windows key + R to open the Run dialog.
• Paste commands secretly copied onto the user's clipboard by the malicious site.
• Execute these commands without realizing that they are harmful.

These pasted commands usually trigger malware downloads, provide attackers with remote access, or compromise sensitive data.

Fake CAPTCHA attacks first appeared in the late twenty teens, but in late 2024 and into 2025 they have surged in popularity among hackers. Security media outlets started reporting more of these attacks being seen in the wild in early 2025.

Why It Matters

These attacks are dangerous precisely because they exploit trust. Users have grown accustomed to solving CAPTCHAs to verify their identity on various websites, making them less suspicious of CAPTCHA requests. Attackers leverage this familiarity to deceive even vigilant users.

Once executed, these malicious scripts can lead to severe consequences, including:

• Data breaches: Exposing personal and sensitive business data.
• Financial loss: Theft of banking information or deployment of ransomware.
• System compromise: Allowing attackers persistent access to infected computers.

How to Recognize Fake CAPTCHAs

Legitimate CAPTCHAs will never:

• Request you to open system utilities like Command Prompt or PowerShell.
• Ask you to copy, paste, or execute commands in your system.
• Require downloading or installing software.

Any CAPTCHA prompt asking you to perform these actions should immediately raise suspicion.

Security Best Practices

To prevent falling victim to malicious CAPTCHA attacks, follow these simple guidelines:

• Stay Vigilant: Be skeptical of unexpected CAPTCHA prompts, especially if they request unusual steps.
• Check the URL: Always verify you are on a legitimate website by carefully examining the URL in your browser’s address bar.
• Avoid Unusual Requests: Genuine CAPTCHAs typically involve selecting images or typing distorted text. Anything beyond this is a red flag.
• Reach Out to IT: Whenever something feels off, stop and contact your IT department for guidance before taking further action.

Fake Captcha Internal Communication Template

To help spread awareness within your organization, feel free to use the following email as a communication template:

Subject: Security Awareness: Beware of Malicious CAPTCHA Prompts

Team,

Recently, we had an incident involving fake CAPTCHAs prompting users to execute commands on their computer. To avoid this:

• Never follow CAPTCHA instructions that involve opening the command prompt, PowerShell, or pasting commands into system dialogs.
• Opening a command prompt happens by pressing the Windows (Start) key + R at the same time. (R for Run)
• If you encounter unusual verification prompts, immediately contact IT before proceeding.

Remember: R for Run and tell IT.

Your awareness helps keep us secure. If something feels off, reach out to us right away.

Thank you,
[Your IT Security Team]

Final Thoughts

Cyber threats evolve constantly, and staying informed is your strongest defense. By recognizing and avoiding suspicious CAPTCHA prompts, you can help maintain the security of your organization’s data and IT infrastructure. Always trust your instincts—if something doesn’t feel right, pause and verify with IT support.

Stay safe, stay vigilant!