# A placeholder domain used in 1,700 code repositories now serves scam content

> The placeholder address third-party.com, used in code and documentation, now serves a ClickFix trap; two similar domains show Mac visitors fake virus alerts.

HisnLabs Security & Research Team (HisnLabs) · Published 2026-09-26
Canonical: https://hisnlabs.com/en/news/placeholder-domains-docs-clickfix-scams

For years, "third-party.com" has been a made-up web address filling documentation and code samples, in the same role as example.com. Someone has since registered it, and it now serves a ClickFix trap to Windows visitors, [The Hacker News reported](https://thehackernews.com/2026/09/placeholder-third-partycom-referenced.html) on 24 September, citing research from Manifold Security. Two similar placeholder addresses show Mac visitors scareware and an investment scam.

## Background

> 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.
>
> — Ax Sharma, head of research at Manifold Security, quoted by The Hacker News

Only example.com, example.org and example.net are formally reserved by IANA for this purpose; addresses like third-party.com merely look generic enough that developers assumed nobody would register them for real use [[1]](https://thehackernews.com/2026/09/placeholder-third-partycom-referenced.html).

## Findings

According to Manifold, the domain has served its lure since at least June 2026. Windows visitors see a fake Cloudflare check that places a command on their clipboard and instructs them to paste and run it; the command fetches and runs a remote PowerShell payload. Mac visitors instead see an error stating that macOS is not supported. A GitHub search finds the domain in more than 1,700 public repositories, including AI agent skills and documentation for MCP servers, the plug-ins that give AI assistants tools, that cite it as an example endpoint. The domain is now flagged as unsafe on VirusTotal and Google Safe Browsing [[1]](https://thehackernews.com/2026/09/placeholder-third-partycom-referenced.html).

Manifold subsequently identified 13 more placeholder-style domains that are not formally reserved. Two of them, yoursite.com and your-domain.com, show macOS visitors scam content while other visitors see an ordinary parking page. The security researcher Cody Nash found that your-domain.com displayed a fake "MacOS Security Center" claiming four infections and offering a counterfeit McAfee renewal, while yoursite.com showed a counterfeit ZDF news article promoting an investment scheme. Those two domains appear in hundreds of thousands of GitHub files and hundreds of AI agent skills [[1]](https://thehackernews.com/2026/09/placeholder-third-partycom-referenced.html).

Manifold notes that an automated file scan cannot see what a website decides to serve to a given visitor: the page looks harmless from an analysis machine and only turns hostile for the intended kind of visitor. Because AI agents now read documentation and follow links on a user's behalf, a placeholder address assumed to be harmless can become an instruction source nobody meant to trust [[1]](https://thehackernews.com/2026/09/placeholder-third-partycom-referenced.html).

> A link that changed hands cannot be told apart by its name alone. Try FireAI free for 17 days: connection prompts show you where an app is really going. [Download FireAI for Mac](https://hisnlabs.com/fireai/en/download)

## Implications for Mac users

In the cases The Hacker News describes, Mac visitors received scareware and scam pages rather than a paste-this-command trap, but the same paste-a-command technique has a well-documented Mac form. A page instructs the visitor to open Terminal and paste one line to "fix", "verify" or "install" something; the line is often unreadable on purpose, either an encoded string or a short command that downloads and runs a script immediately. It works because macOS treats a command a person types or pastes themselves as their own decision: Gatekeeper checks the apps a user opens, not every line run in Terminal.

## Recommendations

1. Never paste a command a web page has placed on the clipboard, regardless of what it claims to fix; this is the ClickFix technique, on both Windows and Mac.
2. Treat a page claiming a Mac has viruses and offering paid protection as a scam, and close it.
3. In documentation, tests or AI agent skills, use only the IANA-reserved names example.com, example.org or example.net, and treat plausible-sounding addresses such as yourcompany.com or your-api.com as domains anyone can register.
4. Audit the links referenced in the skills and documentation loaded by any AI agent or MCP server in use.

## Relevance to FireAI

FireAI shows every connection each app makes, including AI assistants and the local tool servers they launch, on the [world map](https://hisnlabs.com/fireai/en/docs/world-map), so an agent reaching an unfamiliar domain is visible along with the app that triggered it. A domain can be [blocked](https://hisnlabs.com/fireai/en/docs/block-an-app-or-a-company) for one app or for every app, keeping a known-bad placeholder address unreachable. New apps and command-line tools ask before their first connection, and in [Paranoid mode](https://hisnlabs.com/fireai/en/docs/security-modes) even Apple's own command-line tools, the ones a pasted command relies on to fetch a payload, must be approved. [Clipboard Armor](https://hisnlabs.com/fireai/en/docs/clipboard-armor) flags an app's first connection when it lands seconds after the clipboard changed, the timing a clipboard-poisoning page produces.

FireAI does not read web pages or evaluate what a site displays, so it will not identify a fake security alert shown inside a browser; recognising that is left to the user.

> See where an app is really connecting. Try FireAI free for 17 days. [Download FireAI for Mac](https://hisnlabs.com/fireai/en/download)

## Limitations

The report does not state how many people were affected by the third-party.com redirect before it was flagged, nor how quickly VirusTotal and Google Safe Browsing added their warnings after Manifold's disclosure. It is not established whether any AI agent has, in practice, followed one of these placeholder links and acted on the resulting content; the report describes the exposure as a risk arising from how widely the domains are referenced, not a confirmed case of an agent being compromised this way.

Try [FireAI, by HisnLabs](https://hisnlabs.com/fireai/en/download) free for 17 days.

## Sources

- [The Hacker News (Ravie Lakshmanan), 24 September 2026: Placeholder third-party[.]com referenced across 1,700+ repositories now serves malicious content](https://thehackernews.com/2026/09/placeholder-third-partycom-referenced.html)