Mac OS X users should be on the lookout for a virus called Leap. Leap (OS X/Leap, also known as CME-4 ) is not a major threat and is probably getting more media attention than it deserves, but the virus does serve to remind us that not every computer virus is confined to the Windows operating system. That said, Leap does not affect Linux or Unix, although Mac OS X is based, in part, upon Unix. Leap uses the Spotlight search within OS X and looks for the opportunity to spread whenever the iChat app is opened. Fortunately, Leap does not damage system files.

How it works
To become infected with Leap, Mac OS X users will first be asked to open a file pretending to be images from the upcoming OS X release, codenamed Leopard. The victims are sent, via iChat, a file named latestpics.tgz, which, when opened, contains two files. Ironically, due to an error in the internal code and not by design, once latestpics.tgz is opened some Mac applications will fail to run.

Prevention
If asked to accept a file via iChat with the name latestpics.tgz, refuse. By not accepting the file, you can avoid infection.

Removal
A few antivirus software companies have updated their signature files to include this Mac OS X virus. This will stop the infection upon contact and in some cases will remove an active infection from your system. For more information, see McAfee, Sophos, and Symantec.

And just when we think this is an one-off incident, Antivirus vendor F-Secure reported a second Mac OS X pest, Inqtana, which spreads primarily using Bluetooth. Of the two, Mac OS X users should consider Leap to be the greater risk. Leap can cause some Mac applications not to run and, in some instances, crash the infected machine.