BBC News Online: Sci/Tech

Festive e-greeting hides virus

Many will receive e-greetings instead of traditional cards

The worm, called Reeezak has popped up in the United States and Europe and, if activated, could destroy data on personal computers.

The virus has been classed as a medium risk and so far it has not spread widely over the internet.

Anti-virus firm MessageLabs said it had detected just over 1,200 attacks by Reeezak, most of them in the UK.

Hidden danger

It is disguised in the form on an e-mail message with the subject line "Happy New Year," bearing an an attachment called "Christmas.exe" designed to fool the recipient into thinking it is a e-greeting.

The virus also changes the default home page of any copy of Internet Explorer it finds to point to an accompanying website.

Anyone visiting that site will encounter a program that exploits a weakness of Internet Explorer in an attempt to delete the files found in the Windows System directory.

If it suceeds it can render a computer inoperable.

Anti-virus experts say most computer users can expect to receive a flood of e-mails during the festive season.

"Holiday-themed threats, such as Reeezak, remind us that computer users should never let their guard down when using the internet," said Ian Hameroff of anti-virus software firm Computer Associates.

"Be on the lookout for suspicious messages, they may be bearing gifts that you don't want," he said.

Computer Associates has rated the worm, which is also known as W32/Zacker.C@mm and W32.Maldal.C@mm, as a medium to high risk.