Those trying to access Bing today over a secure connection will be met with a security certificate issue. At present, the most likely explanation is an issue with Microsoft's certificate provider of choice, Akami, suggested by a tweet from Jon Brodkin.
Using Chrome, attempts to access Bing with an secure HTTPS connection will be met with this glaring security message:
You attempted to reach bing.com, but instead you actually reached a server identifying itself as *.bing.com.
The message goes on and attempts to explain the error:
This may be caused by a misconfiguration on the server or by something more serious. An attacker on your network could be trying to get you to visit a fake (and potentially harmful) version of bing.com.
Despite the sinister warning, clicking "proceed anyway" takes you to Bing.com, not to the underground internet bunker of an illicit hacker.
You can replicate the error by navigating to Bing.com using the 'https' prefix. Depending on what browser is being used, a security warning will usually pop up. The issue is consistent throughout all four browsers tested, including IE, Firefox, Safari and Chrome.
We've reached out to Microsoft regarding the issue, but have had no reply thus far; the article will be updated following any contact from the company.