You’re using Google or another browser and up pops a window that looks official.
It says
Some suspicious activity has been detected at your IP address.
Cydoor spyware may have caused a network breach at your location.
Personal and financial information may be at risk.
Call toll-free 0800-014-8212
Please contact a certified Microsoft technician to rectify your situation
Please do not attempt to close your browser or open another one in order to avoid corruption of your operating system.
A second popup claims that multiple high risk infections have been detected and my credit card information is at risk. So I must call the toll free number.
This is just a scam. The phone number isn’t for a Microsoft certified professional, it’s a scammers number and they will then convince me to let them take control of my PC and end up paying a lot of money to remove non-existent problems.
Don’t fall for this. If you see these kinds of messages – disconnect the Internet and shut down the computer then restart it and run an anti-virus scan.
If you are in any doubt as to whether your computer has a virus – then take it to a professional but do not call the phone numbers in the popups.