Trojan Horse for Mac OS X

The existence of a Trojan Horse that attacks Mac OS X has been known since March 20th, but it wasn't reported until yesterday. Called MP3Concept or MP3Virus.gen, the Trojan masquerades as an MP3 file. It hides in ID tags and activates when the user clicks to play a song.

The Trojan appears to be the first malicious code for Mac OS X, which was launched in March 2001.

Until now, Mac users have prided themselves on running a system that has been largely virus-free. Few Mac OS X users run antivirus software, or are wary of double-clicking files they've downloaded or received in e-mail.

That could change quickly. Nearly half of the executable files downloaded through Kazaa contain malicious code like viruses and Trojan horses, according to a recent study by security firm TruSecure. Out of 4,778 files downloaded in one month for the study, nearly half contained various types of nefarious code.

Mac users are cautioned not to open email attachments unless they were expected. More malicious code is expected in the future to specifically target Mac machines.