New Trojan Horse Targets Mac OSX

The first trojan horse virus to affect Mac OSX has been detected, and a leading Mac security firm has released an anti-virus update to combat it.

Intego, the Macintosh security specialist, has just released updated virus definitions for Intego VirusBarrier to protect Mac users against the first Trojan horse that affects Mac OS X. This Trojanhorse, MP3Concept (MP3Virus.Gen), exploits a weakness in Mac OS X where applications can appear to be other types of files.

The Trojan horse’s code is encapsulated in the ID3 tag of an MP3 (digital music) file. This code is in reality a hidden application that can run on any Macintosh computer running Mac OS X.

Mac OS X displays the icon of the MP3 file, with an .mp3 extension, rather than showing the file as an application, leading users to believe that they can double-click the file to listen to it. But double clicking the file launches the hidden code, which can damage or delete files on computers running Mac OS X, then iTunes to play the music contained in the file, to make users think that it is really an MP3 file . While the first versions of this Trojan horse that Intego has isolated are benign, this technique opens the door to more serious risks.

This Trojan horse has the potential to do any of the following:
– Delete all of a user’s personal files
– Send an e-mail message containing a copy of itself to other users
– Infect other MP3, JPEG, GIF or QuickTime files

Due to the use of this technique, users can no longer safely double-click MP3 files in Mac OS X. This same technique could be used with JPEG and GIF files, though no such cases of infected graphic files have yet been seen.

Intego VirusBarrier eradicates this Trojan horse, and Intego remains diligent to ensure that VirusBarrier will also eradicate any future viruses that may try to exploit this same technique. All Intego VirusBarrier users should make sure that their virus definitions are up to date by using the NetUpdate preference pane in the Mac OS X System Preferences.