When you see a subdomain like cdn.office.net.mcas-gov.us, the name suggests a Microsoft Cloud App Security endpoint for US government customers. The security side checks out: a current Microsoft-issued certificate, modern HTTPS enforcement, and no malware flags. But here's the catch — the WHOIS database returns no information at all for this .us domain. For a site that likely handles government authentication traffic, that lack of ownership transparency is unusual. Legitimate government domains almost always have clear registrant data.
Microsoft is a massive company and this subdomain could be a legitimate piece of their government cloud infrastructure. But without public WHOIS, you can't independently verify who controls it. If you're an IT admin being redirected here for single sign-on, double-check the URL against your Microsoft 365 Gov tenant settings. For everyone else, treat it with the same caution you'd use for any site that obscures its ownership, even if the technical protections look fine. There's not enough evidence to call it a scam, but there's also not enough to fully trust it.