While President Obama is at Stanford's cybersecurity summit, he's letting his own cybersecurity lapse. Anyone attempting to visit WhiteHouse.gov over HTTPS is currently seeing the error message above, thanks to a kitchen-sink web security error on the part of the White House digital team. You can see the yourself if you head to https://www.whitehouse.gov/ in Chrome. (Don't forget the "https" part; it's important.)
The error seems to be coming from a Common Name mismatch, essentially a misconfiguration that made the White House's certificate just suspicious enough to set off Chrome's alarms. As a result, Chrome spent the day blasting out a warning not to trust the White House. Awkward!
2/13 2:16pm ET: Updated to clarify the cause of the error. A previous version inaccurately stated that the certificate had expired.