The domain "third-party[.]com", long a generic placeholder in documentation, has been observed serving a sophisticated **ClickFix** lure. This attack specifically targets Windows browsers, while displaying a harmless decoy to other operating systems. **Ax Sharma**, Head of Research at **Manifold Security**, explained the inherent risk: "'third-party[.]com' has been a generic documentation placeholder for years, the same role example.com plays. Unlike 'example[.]com,' third-party[.]com is not **IANA-reserved**. Anyone could register it, and someone did. Every doc, test, and skill that hard-coded it now points readers at attacker infrastructure." As of writing, the domain has been flagged as malicious and unsafe by **VirusTotal** and **Google's Safe Browsing** list. ### Understanding ClickFix Attacks **ClickFix** is a social engineering technique where compromised or malicious websites display fake error messages, browser alerts, or CAPTCHA prompts. These prompts trick users into copying and executing hidden commands via the Windows Run dialog or Terminal to "fix" the non-existent issue. Often, **ClickFix** pages employ clipboard hijacking, automatically injecting malicious scripts or commands into the victim's clipboard for subsequent pasting. This method is also known as pastejacking. ### The 'third-party[.]com' Incident According to **Manifold Security**, the domain has been serving the **ClickFix** lure since at least June 2026. Windows users visiting the page are presented with a fake **Cloudflare** check designed to poison their clipboard. They are then instructed to paste and run a command via the Windows Run dialog, which executes a remote PowerShell payload. In contrast, macOS users visiting the same page encounter a deceptive error message: "macOS is not supported. This website requires a Windows PC to access. Please try again from a Windows device."  ### Widespread Impact and Further Discoveries A search on **GitHub** reveals that "third-party[.]com" is referenced in over 1,700 public repositories, including those related to AI agent skills and MCP-server documentation, where it's cited as an example endpoint. Sharma emphasized the danger: "In every one of those places it is exactly what it looks like: a placeholder, an example, a stand-in, and entirely reasonable use by the teams involved. It is also, now, a live pointer to a **ClickFix** server." This weaponization of a trusted domain can open avenues for prompt injection and other unintended behaviors, particularly in the context of AI agents. ### Recommendations for Mitigation To counter this threat, organizations are advised to audit their documentation and treat non-reserved placeholder domains (e.g., yourcompany[.]com, mycompany[.]com, your-api[.]com, and similar lookalikes) as potentially vulnerable to squatting and abuse by threat actors. Developers are strongly recommended to use only **IANA-reserved** placeholders such as "example[.]com" (or "example[.]org," "example[.]net") and avoid using plausible-sounding domains not under their direct control. **Manifold Security** highlighted a critical blind spot: "You can scan the skill, read the file, resolve the domain from your analysis box, and conclude it is fine, and be completely wrong about what a Windows user's agent receives when it follows the same link. A file scan cannot see what a website decides to send. The tell only appears at request time, from the caller that matters." ### More Placeholder Domains Identified **Manifold Security** has since identified 13 additional non-**IANA-reserved** placeholder domains. Two of these – "yoursite[.]com" and "your-domain[.]com" – are actively serving scams and scareware to macOS visitors, while showing ordinary parking pages to others. **Cody Nash**, a security researcher, detailed the findings: "On a macOS browser, your-domain[.]com showed a fake 'MacOS Security Center' claiming four viruses and selling a counterfeit **McAfee** renewal at 55% off. On another macOS render, yoursite[.]com showed a counterfeit **ZDF** news article advertising an investment scheme."  The complete list of identified domains, all of which pass standard static checks, includes: * your-domain[.]com * yourdomain[.]com * your-site[.]com * yoursite[.]com * your-app[.]com * yourapp[.]com * myapp[.]com * mysite[.]com * acme[.]com * company[.]com * mycompany[.]com * vendor[.]com * foo[.]com These scam-serving sites are present in hundreds of thousands of **GitHub** files and numerous agent skills. Nash concluded, "Scareware and investment fraud are a lower threat than clipboard malware, the exposure they ride on is far larger, and none of it showed up in any static check we ran."