Barracuda reports attackers are abusing fake CAPTCHA pages as a “trust step” to push victims into credential theft, malware downloads, and enabling malicious browser notifications. In some “ClickFix” variants, the CAPTCHA flow tricks users into pasting and running a command on their own Windows device, which then starts the infection.
Key findings
- Barracuda observed CAPTCHA abuse in a large portion of phishing-kit attacks it reviewed in 2025.
- A common flow uses an email lure (document/invoice/contract) that leads to a CAPTCHA gate and then to a fake Microsoft 365 sign-in page to steal credentials.
- Some campaigns use fake CAPTCHAs to trigger malware downloads or to persuade users to enable browser notifications for follow-on malicious content.
- ClickFix-style fake CAPTCHA pages can copy a command to the clipboard and then instruct the user to paste/run it, initiating infection.
- Attackers may chain multiple brand impersonations (e.g., CAPTCHA → Adobe-style prompt → Microsoft sign-in) to resemble normal workplace steps.
Who’s being targeted
- Commonly targeted roles: All employees, Finance and Accounts Payable, Procurement, Legal, Executive assistants, IT helpdesk (for user reporting/triage).
- Affected industries: Cross-industry (any organization using email, document sharing, and Microsoft 365).
- Attack channels: email, website.
- Impersonated: Document sharing/workplace portal leading to Microsoft 365 sign-in, Fake CAPTCHA / fake browser or document error page, Website presenting a CAPTCHA or access gate.
Awareness takeaways
- Treat unexpected CAPTCHAs as a warning sign, especially when they appear before viewing an invoice, contract, or shared file.
- Never run commands or “fix steps” provided by a webpage, report it to IT/Security instead.
- Watch for brand-impersonation chains (CAPTCHA → Adobe-like prompt → Microsoft sign-in) designed to feel like normal work steps.
- Verify the website address before entering credentials or following instructions, and be cautious of misspellings or odd subdomains.
Red flags to watch for
- Unexpected CAPTCHA gate before viewing a routine document
- Sign-in page is a “counterfeit Microsoft 365 login page”
- Pressure to proceed to avoid “account suspension or data loss” themes
- A webpage instructs you to run a command on your computer
- The site copies text to clipboard without clear permission/need
- “Recovery instructions” that involve system tools for a simple CAPTCHA
- CAPTCHA/access page asks to enable browser notifications
- Unexpected prompts to allow notifications on a document/invoice page
- Follow-on “further malicious content” delivered via notifications
Read the video transcript
You click an invoice link, and before anything loads, boom, full-page CAPTCHA: “Verify to view document.” That fake CAPTCHA is the trust trick. After you click it, you land on a counterfeit Microsoft 365 sign-in, sometimes even after an Adobe-style prompt, built to steal your password. The nastier ClickFix versions go further: you click 'Verify', it silently copies a command, then tells you, step-by-step, to open Windows Run, paste, and hit Enter, so you infect yourself. If a ‘CAPTCHA’ leads to a login page or tells you to run a command, stop. Close it and report it to IT or Security, don’t click, don’t paste, just report.