Not all hackers spend hours cracking passwords to break into your system; sometimes, you invite them right in.

The latest cyberscam involves the criminals ringing you up on your phone.

Microsoft says crooks posing as computer engineers are calling people at home, telling them they're at risk of some cyber threat.  Often, the hackers were so believable, they convinced the victims to actually give them remote control of their computers.

Greg Evans with NationalCyberSecurity.com says at that point, the phone call may end quickly, but the damage is done.

"When these people are accessing the computer remotely, they're installing spyware on there," says Evans.  "So everything that you do on your computer--every user name, password, e-mail address, every bank account number--is being e-mailed to this hacker that you gave full access to."

The criminals also sounded legit because they often used telephone directories to call their victims by name.

Sometimes, the victims gave their credit card number to the con men in order to buy something.  More than one out of every five who got the phone call, 22%, were conned into handing over their financial information or computer's control.

The Microsoft survey says the average victim lost $875 before figuring out they had been scammed.  Losses ranged from as low as $82 in Ireland up to $1,560 in Canada.  Seventy-nine percent of those who fell for the "security expert" calls said they had suffered a financial loss.

Evans says the warning bells should go off immediately when someone calls you, telling you that your computer is at risk.  He says the easiest thing to do is just to hang up the phone, the same way you would slam the door on a stranger who showed up at your doorstep saying he was a plumber who needed access to your house.

"People who are giving up their personal information are the same people that I believe would turn around and believe those Nigerian e-mails [stating] 'I'll give you $50 million if you give me $5,000,'" he says.