If you get a phone call from someone wanting to help you fix a computer security "threat," hang up fast. The call is likely part of the latest scam targeting computer users.

Microsoft Corp. on Thursday released findings of a survey that found 15 percent of consumers in four English-speaking countries, including the U.S., have received the calls.  Microsoft surveyed 7,000 computer users in the U.K., Ireland, U.S. and Canada; 15 percent of those surveyed said they had received such a call.

The scam works like this: Someone posing as computer security engineer calls people at home and warns they are at risk of a computer security threat. The scammers say they are providing free security checks and claim to represent legitimate companies; they use telephone directories to call their intended victims by name.

Of those who received a call, 22 percent were tricked into following the caller's  instructions -- permitting remote access to their computer, downloading software code provided by the criminals or providing credit card information and making a purchase.

Of those who fell for the scheme, 79 percent suffered some sort of financial loss; 17 percent said they had money taken from their accounts; 19 percent reported compromised passwords and 17 percent were victims of identity fraud. More than half  said they suffered  computer problems as a result of the incident.

The average amount of money stolen was $875, ranging from $82  in Ireland to $1,560 in Canada. The average cost of repairing damage caused to computers by the scammers was $1,730 and  a whopping $4,800 in the U.S.

The Guardian newspaper in Britain reported that the scheme has been around since 2008 but has been growing in scale in the past year. The Guardian said the scam is being run by call centers based in India.