There are lots of different kinds of malware out there, most of which are interested in hiding behind the scenes. After all, the point is to avoid being discovered and removed. The longer they stay on your computer, the more information these programs can send back to their creators. Or the malware can continue sending out spam or creating denial-of-service attacks.

Bob Sullivan wrote a post in MSNBC’s The Red Tape Chronicles that discusses a particular type of malware that fully intends to get your attention. It’s called ransomware, and it does pretty much exactly what it sounds like. It locks up your computer until you pay off the creators. It’s not a new concept — Steven J. Vaughn-Nichols said the idea has been around since the 1980s. But as he and Sullivan point out, ransomware is becoming meaner and more common now than in years past.

According to Panda Security researcher Luis Corrons Granel, one ransomware package called TotalAntivirus has one-fourth of all of these infections. The program demands a license fee of $50 for two years or $79 for a lifetime. Another program Sullivan mentioned encrypts your files. You can use your computer, but if you want your files back, you’ll have to pay the ransomers’ demands.

John Leyden of The Register wrote a few weeks ago about a Russian program holding computers for ransom. To get their machines free, victims have to send an SMS message to a premium text messaging number.

Of course, the hackers have to get this program onto your computer, and to do that, they use good old fashioned social engineering tricks, such as URL poisoning. Sullivan quoted a Symantec security researcher named John Harrison as saying malware hackers used false URLs to trick people searching for information about the recent Haiti earthquake to download these ransomware programs to their computers.

The authors of these programs also like to use pop-up windows warning you that there’s some kind of malware on your machine. Don’t click on the window. Close it with a keyboard command or by clicking on your taskbar instead. The windows are likely rigged to make any click an installation request. Scan your computer periodically for malware, but don’t forget to keep your antivirus definitions up to date.

So what happens if your machine is already infected? Unplug it from the Internet so the malware can’t share your personal information with the program’s creator. Sullivan advised users to use another computer to find a good solution, and many reputable antivirus software vendors offer programs that will clean the ransomware off your machine for free. You’ll have to put it on a thumb drive or CD, but that’s cheaper and better than paying the hackers. And trusting them with your personal information.