Odd anomaly caused Microsoft’s network to mishandle example.com traffic

In a surprising turn of events, Microsoft has disclosed an unusual anomaly within its network that has been misrouting traffic intended for example.com, a domain designated specifically for testing purposes. Instead of the expected behavior, this traffic has inadvertently found its way to a Japanese electronics cable manufacturer, Sumitomo Electric. According to RFC2606, an official standard from the Internet Engineering Task Force, example.com is not meant to be accessible over the Internet. This domain is intended solely for local network use to prevent developers and testers from unintentionally impacting third parties during their work. The guidelines encourage the use of example.com, along with two other domains—example.net and example.org—for such activities. Recent terminal command outputs, specifically from cURL, have revealed that certain traffic on Microsoft’s Azure and associated networks has been routed to subdomains of sei.co.jp, the domain owned by Sumitomo Electric. The unexpected results were particularly evident in the JSON-based responses generated on Friday. Furthermore, attempts to create test accounts using test@example.com in Outlook exhibited similar misrouting, sending data to the subdomains imapgms.jnet.sei.co.jp and smtpgms.jnet.sei.co.jp. This peculiar behavior stems from Microsoft’s autodiscover service. Michael Taggart, a senior cybersecurity researcher at UCLA Health, noted, "While I’m not deeply versed in Microsoft’s internal processes, this seems to be a straightforward misconfiguration. Consequently, anyone setting up an Outlook account linked to an example.com domain may unintentionally send their test credentials to these sei.co.jp subdomains."