CryptoLocker virus holds your computer for ransom

A KILLER virus is making its way through the world's computer's, corrupting files and demanding a ransom to get them back. There's only one way to protect yourself.

The virus message that pops up.

ONLINE hackers have a new reason to break into your computer - your cold, hard-earned cash.

A nasty new virus called CryptoLocker is infecting computers around the world - encrypting important files and demanding a ransom from their helpless owners to unlock them.

The ransom note pops up flashing on the computer screen, and the victim is given 72 hours to cough up the casg, or the files will be permanently deleted. A countdown clock indicates how much time you have left to pay the fee.

The amount demanded is usually $300, or two Bitcoins (approximately $US260 each).

"It systematically hunts down every one of your personal files - documents, databases, spreadsheets, photos, videos and music collections - and encrypts them with military-grade encryption and only the crooks can open it," a senior security adviser at worldwide digital security company Sophos, Chester Wisniewski, told NBC's Today program.

Once infected, your computer keeps working normally, but you can't access any of your personal files. It's terrifying if you haven't backed up your data.

"Cybercrime is evolving, as the bad guys get smarter and use newer technologies," said Michael Kaiser, executive director of the National Cyber Security Alliance. "They're always looking for new ways to steal your money."

"The author of this [malware] is a genius. Evil genius, but genius none the less," an IT professional commented in an online tech forum. Another wrote, "This thing is nasty and has the potential to do enormous amounts of damage worldwide."

Online forums like BleepingComputer.com are filled with horror stories of people and businesses losing important data and precious memories.

"The virus cleverly targeted…all of our family photos, including all photos of my children growing up over the last eight years," wrote one victim. "I have a distraught wife who blames me!"

A business had 180,000 files encrypted after the virus infected one worker's computer. The company had to shut down for two days, and eventually ended up paying the ransom fee.

So how do you protect yourself and your computer? Aside from caving and paying the ransom, defence and prevention is the only safe method.

"Backup, back, up, back up," said former White House Cyber Security Advisor Howard Schmidt. "That's the only way to reduce the risk of losing your files forever."

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