It’s easy to become blasé about internet security threats, but if you find yourself infected by a new one that’s just appeared, you’ll have a very expensive problem on your hands.

Discovered by security specialist Kaspersky Lab , the virus uses a virtually unbreakable 1024-bit algorithm to encrypt all the data on your PC. The only way to regain access is to pay the anonymous author a hefty ransom.

Called Gpcode, the virus encrypts a range of files including Word documents, PDFs, text and image files. While such internet-borne viruses are not new, the massive strength of this latest version means it poses a very real threat to both business and consumer internet users.

According to Kaspersky Lab, its security researchers have been able to break previous incarnations of the virus because they had used either 260-bit or 330-bit algorithms to encrypt data. However this latest 1024-bit version has them worried as they haven’t been able to come close to cracking it.

Like most virus attacks, this one is most likely to come in the form of a spam email message with an attachment. Clicking on the attachment installs a Trojan install application which then downloads the Gpcode virus from a website.

Once it’s locked up your files, any attempt to open them triggers a message telling you to email a particular address to arrange ‘purchase’ of a decryption tool.

The bottom line is that, if you get infected, you’ll have to choose between paying the ransom demand or waving goodbye to your data. Not a nice choice to have to make.

This latest online threat makes it even more critical to ensure internet security software is up-to-date and that you resist clicking on attachments from unknown sources.

Kaspersky Labs urges anyone hit by the virus to contact them with details of when the attack took place and which web sites the user had been visiting at the time.