Bogus Microsoft employees have stolen thousands of dollars in a 24-hour sting in New Zealand.
Police say the scam artists - working offshore - were cold-calling people and warning them viruses had been detected on their home computers.
At least two people in Alexandra fell for the ruse and lost thousands of dollars.
The fraudsters called and asked for remote access to the computers to fix the problem - and then asked for credit card information.
NetSafe operations manager Lee Chisholm said such scams had been occurring throughout New Zealand for the past three or four years.
"Sometimes they say they're Microsoft, sometimes they say they're Windows, sometimes they say they're Spark, but the story's always the same: that there's something wrong with your computer and you need to give us access immediately because if you don't your computer will crash and corrupt other computers."
The scammers then directed the victim to a legitimate website that allows remote access to their device.
"Then they get access to your computer, muck around, sometimes for over an hour and then say, "Okay we've secured your computer and now you will be secured for the next two years. That will cost you $500, what's your credit card number'?"
During the time they were on the computer they would be able to clone the whole device, Chisholm said. "It's very difficult when it's elderly people. They're particularly vulnerable."
Police urged anyone who received such approaches to take the caller's information and report them to police and to NetSafe.