Microsoft Official Support (aka Important Security Message) is a phishing site that pretends to be an official Microsoft tech support website. It is usually targeted at Google Chrome users. It tells the user that their computer has been locked due to it being "infected by a virus", even when the computer is safe. This scam appears on many URLs (typically on parts of AmazonAWS.com) and has many descriptions. The type of virus may vary.
Once the website is viewed, it opens a fake Microsoft support webpage topped by a message saying that your computer has blocked by the visited website due to it being "infected" by a so-called "virus". Below the error code would be a phone number followed a list of information claimed to be at risk.
Clicking on the X button won't do any help since the window is locked, but it can be closed by restarting your computer, or through the task manager.
- A green version exists. This version is not as bad as the others and is easier to remove, as this version does not lock the window.