Let me save you the suspense. If someone calls you out of the blue and says they are from Microsoft, or Windows, or Apple, and that your computer has a virus, it is a scam. There is no version where that call is real. Microsoft does not monitor your personal computer, does not know your phone number, and will never call to warn you about an infection.
It is worth understanding why these calls work, because the people who fall for them are not careless. They are usually careful, and that is exactly what the scam uses.
The scam is manufacturing panic and then offering to be the calm one. A stranger tells you something is wrong with your computer, your files, your bank. Then, before you can think, that same stranger offers to fix it. They sound official. They have a script. They may even walk you to a screen full of harmless warnings and point at them as proof. The whole play is to keep you moving fast enough that you never stop and ask the obvious question, which is how a company you never contacted knows anything about your machine.
The pop-up version is the same trick in reverse. They get you to call them. A page takes over your screen, sometimes with an alarm sound, and tells you to call a number right now or you will lose access to your computer. That number does not go to Microsoft. It goes to the same room of people making the phone calls. A real security warning from your computer never asks you to phone anyone.
Once they have your attention, they will ask you to let them connect to your computer with remote software, and then they want to be paid. Sometimes it is a fake fee to remove problems that were never there. Often while they are connected they go looking for banking sites and passwords. When a stranger on an unexpected call wants remote access to your machine, it's time to end the call and reach out to someone you trust.
The solution is simple. If it is a phone call, hang up. You do not owe them a conversation and you do not need to explain yourself. If it is a pop-up, do not call the number and do not click the buttons inside it. Close the browser, and if it will not close, restart the computer. If you are ever unsure whether a warning is real, the safest move is to contact a person you already trust, not the number on the screen.
If you already let one of them in, do not panic, but do act. Disconnect the computer from the internet, change the passwords for anything important (from a different device) and if money or your bank was involved, call your bank directly. Then have someone check the machine to make sure nothing was left behind.
There is a reason I keep coming back to this one. In all my years fixing computers, the calls and pop-ups have gotten slicker, but the tell has not changed. Real help does not come to you uninvited and demand access in a hurry. If you want the fuller version of what a legitimate tech will and will not ever ask you to do, I wrote that up here: what a legit tech support company will never ask you to do.
If you think you let one of them in, stop and call me before you do anything else. That is a good reason to pick up the phone, and the sooner the better.
Mike
PCRescue | Portland, ME
Those "Microsoft Support" Calls Are Always a Scam
If someone calls saying they are from Microsoft and your computer has a virus, it is a scam. Every time, no exceptions. Here is how it works and how to shut it down.