Mac Users Face First Apple Virus

Users of Apple computers were today being warned to protect themselves after the existence of a new kind of worm virus emerged.

The Leap-A worm, which spreads through instant messaging program iChat, is thought to be the first virus for the Apple platform. It poses as a series of pictures which, when opened, allows the worm through a security loophole in order to implant itself in other programs.

Experts say it is easy for users to protect themselves, but that the arrival of malicious code should be a wake-up call to Mac users, who have been unaffected by viruses until now.

"The Leap-A worm isn't in itself a significant threat, but it should act as a helpful reminder that malware [malicious software] can be written for any computer," said Graham Cluley of anti-virus company Sophos.

"The bad news is that most people think the situation is going to get worse for Macintosh users, and more threats will be targeted against the Apple community. The good news is that most don't believe it will ever be as big a problem as the one Microsoft Windows faces."

Microsoft's Windows, which commands more than 90% of the home computer market, is a far more established target for virus writers. As many as 200 new pieces of malicious Windows code are discovered every day, but until now hackers have shied away from attempting to infiltrate Apple machines. Experts believe, however, that the recent popularity of the company's iPod music player could have spurred the arrival of Leap-A.

It is 20 years since the first widespread PC virus, Brain, hit computers around the world. But despite the lack of Apple viruses in the wild, users have been warned on previous occasions to be wary of potential threats. Bill Thompson, a technology columnist for the BBC, recently came under fire for saying that Mac owners were "too smug" about security issues.

· Charles Arthur, the editor of Technology Guardian, gives more detail about the worm here