Microsoft Australia warns against CryptoLocker Virus

It's targeting businesses and making it impossible to access  files -- it's called CryptoLocker. CryptoLocker is a computer virus that quietly installs and encrypts files, which makes it harder to access them, but there's a catch -- in order for you to access these files you must pay up or lose it forever.

Computer Expert Jamie Mellis says the instructions are specific. A message says there's a private key on a secret server on the internet that will allow you to restore your files as long as you pay up by the deadline with an untraceable credit card.

"It's targeting businesses. It also goes after things like music files and pictures as well," Mellis said.

If those files are infected by the virus it can be devastating especially if you don't have them saved anywhere else. Mellis said he encounters people on a daily basis with absolutely no backups and unfortunately in many cases there's nothing he can do to recover the files. The CryptoLocker virus is spreading through phony FedEx and UPS tracking notifications and other emails pretending to come from legitimate businesses.

The use of online currency makes it difficult to track those responsible for the attacks, because they operate through online exchange networks. Anti-virus company Kaspersky has warned users that paying the ransom is no guarantee you will get your files back.

Experts recommend regularly backing up computer files, and keeping external storage (such as USB thumb drives) unplugged when not in use. In some cases an anti-virus program may remove the virus after it has already locked some of the files.

When this happens, a desktop wallpaper is displayed telling users they need to download the virus again if they want to access their files. There is no known way to recover files already encrypted by the virus. One way to circumvent the timer is to roll back your computer's clock, which can trick the timer. The virus also warns the user not to disconnect from the internet, or turn their computer off.

The virus often takes hours to lock files, and turning your computer off can be the first step in a successful defence. Users are urged to run anti-virus programs immediately, which are often able to remove cryptolockers. They cannot recover files. There are programs that claim to prevent cryptolocker from working, but their effectiveness is uncertain. Some of the criminals behind cryptolocker have eased ransom restrictions - but require the user to pay ten times the amount if they pass the deadline.

In order to 'facilitate' the ransom process, they even launched a customer service website. The virus usually affects systems using older versions of windows, including windows 7, but a call has been issued for both Windows 8 and Mac users to be wary.

Those who have paid the ransom, typically $300, report their files are decrypted within a few hours. Those who didn't, have had to wipe their hard drives clean and restore them before they were usable again.