Affected Systems

Over 1,700 public GitHub repositories referencing third-party[.]com as a documentation placeholder. Additional 13 non-reserved placeholder domains identified (yoursite[.]com, your-domain[.]com, acme[.]com, etc.), with two serving scams/scareware. Affects AI agent skills, MCP-server docs, and test cases that hard-coded these domains.

Exploitation Status

Active exploitation confirmed since at least June 2026. The domain serves ClickFix malware lures to Windows browsers (clipboard hijacking leading to remote PowerShell payload execution). Two additional domains (yoursite[.]com, your-domain[.]com) actively serving scareware and investment scams to macOS users. Domain flagged as malicious on VirusTotal and Google Safe Browsing.

Business Impact

Organizations using affected repositories face supply chain compromise risk. Windows users visiting documentation or executing AI agent skills referencing third-party[.]com may unknowingly execute malicious PowerShell payloads via clipboard hijacking. Static analysis and file scans cannot detect this threat as malicious content is served dynamically based on user-agent. Hundreds of thousands of GitHub files reference the scam-serving domains, creating widespread exposure. Potential for prompt injection attacks in AI systems using these placeholder endpoints.

Urgency

🔴 Immediate

Recommended Actions

  • Audit all internal documentation, code repositories, and AI agent skills for references to third-party[.]com and the 13 identified non-reserved placeholder domains (yoursite[.]com, your-domain[.]com, acme[.]com, mycompany[.]com, vendor[.]com, foo[.]com, etc.)
  • Block third-party[.]com, yoursite[.]com, and your-domain[.]com at DNS/proxy level immediately to prevent user access
  • Replace all non-reserved placeholder domains in documentation and code with IANA-reserved domains: example[.]com, example[.]org, or example[.]net only
  • Review Windows endpoint logs for PowerShell execution originating from clipboard or Run dialog, particularly mshta.exe or powershell.exe with encoded commands, since June 2026
  • Educate development teams on supply chain risks of using uncontrolled placeholder domains and enforce use of reserved domains in coding standards