Fake CAPTCHA (ClickFix) Social Engineering Used for Fileless Malware Delivery
Security researchers reported an active malware distribution technique that abuses bogus CAPTCHA pages to trick users into executing attacker-supplied commands on Windows. In the ClearFake campaign analyzed by Expel, victims land on a compromised site and are instructed to press Win + R, then paste and run a clipboard-seeded command—an approach commonly referred to as ClickFix—which results in malicious PowerShell execution. The campaign emphasizes living-off-the-land tradecraft and evasion, including proxy execution by abusing the trusted Windows script C:\Windows\System32\SyncAppvPublishingServer.vbs to launch PowerShell in hidden mode and reduce the chance of AV detection.
Separate measurement and telemetry on the same broader tactic found large-scale infrastructure supporting fake CAPTCHA lures: a Censys analysis identified 9,494 breached websites hosting counterfeit verification pages, with ~70% appearing nearly identical. The most common infection mechanisms involved clipboard manipulation leading to VBScript and PowerShell execution (with significant counts of each observed), alongside other delivery paths such as MSIEXEC-based installation of malicious Windows Installer packages. Researchers also observed use of the Matrix push command-and-control framework to support fileless deployment, noting that these intrusions can leave no traditional executable artifacts and may evade signature-based detection.
Timeline
Jan 27, 2026
Researchers disclose ClickFix variant abusing App-V and Google Calendar
Researchers reported a new ClickFix-style campaign that abuses the signed Microsoft App-V script SyncAppvPublishingServer.vbs instead of launching PowerShell directly. The attack used a public Google Calendar ICS file as a dead-drop resolver, then staged in-memory payloads that ultimately launched Amatera Stealer.
Jan 27, 2026
Expel details ClearFake's ClickFix and proxy-execution techniques
Expel researchers disclosed that ClearFake uses fake CAPTCHA prompts to trick users into pasting malicious PowerShell commands from the clipboard into the Windows Run dialog. They also described the campaign's use of the legitimate SyncAppvPublishingServer.vbs script for hidden proxy execution and estimated nearly 150,000 infections since August 2025.
Jan 26, 2026
Censys identifies thousands of breached sites hosting fake CAPTCHA lures
Censys analysis found 9,494 compromised websites serving bogus CAPTCHA pages used for malware distribution. Researchers observed several delivery chains, including clipboard-injected PowerShell and VBScript, MSIEXEC-based installers, and Matrix Push for fileless deployment.
Nov 18, 2025
Darktrace detects and blocks ClearFake activity on a customer device
On November 18, 2025, Darktrace observed likely ClearFake activity on a single device, including mshta.exe execution, Smart Chain-related requests, and attempts to retrieve payloads from suspicious infrastructure. Darktrace said its Autonomous Response blocked the outbound connections and likely prevented delivery of an information stealer.
Aug 1, 2025
ClearFake infections begin scaling via blockchain-backed delivery
Based on smart-contract transaction history, Expel assessed that the ClearFake campaign had been infecting systems since August 2025. The operation used EtherHiding on the Binance Smart Chain and other resilient hosting methods to support large-scale malware delivery.
Jun 1, 2023
ClearFake campaign first identified using fake browser updates
ClearFake was first identified in mid-2023 as a malicious campaign using injected JavaScript on compromised websites, often WordPress sites, to trick users with fake browser update and CAPTCHA-style lures. Victims were commonly driven to these sites through SEO poisoning.
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