statics.teams.cdn.office.net

What it is

A Microsoft-hosted page that Teams uses to check links when someone clicks them. The page shows "Checking link" with Microsoft Defender for Office 365 branding, then forwards the browser to the real destination.

Why there's no full URL

The visitor arrives from Microsoft's link-checking page, not from the Teams message, so the referrer is that page. Browsers send only its origin to other sites by default, so there's no path.

What traffic it represents

Someone clicked a link to your site in a Teams chat or channel, in an organization where Defender for Office 365 Safe Links checks Teams links.

Sources

Safe Links checks a list of known, malicious links when users click links in Microsoft Teams.

Complete Safe Links overview for Microsoft Defender for Office 365

en: "Checking link",

Teams Safe Links page strings (Microsoft CDN)

window.location.replace(response.redirectUrl);

Teams Safe Links page script (Microsoft CDN)

For cross-origin requests send the origin (only) when the protocol security level stays same (HTTPS→HTTPS).

Referrer-Policy header - MDN