The Lite Side

Switchback Virus Infects Macs, Nobody Notices

- 2003.08.13

It had to happen sooner or later. There's no glory in creating Windows worms any longer - and script kiddie can do it, and there are more holes in Windows than in a warehouse of Swiss cheese.

No, someone finally wrote the first new Mac virus in nearly a decade, the first one to specifically target OS X. Rumors lead us to believe the malware was written by a disgruntled Windows programmer at Microsoft who was sick to death of hearing how Macs never got infected with viruses, worms, Trojans, and the like.

Or maybe it was just some hapless IT guy upset because one of his clients switched from Windows to the Mac and no longer needs the kind of support they did with the OS from Redmond.

Or maybe it was someone at one of the antivirus companies upset that Mac users weren't buying enough copies of their antivirus software.

Whatever, the Switchback virus exists, and it's spreading like molasses in January.

Yep, that fast.

Switchback is one very clever virus, but it's having a hard time distributing itself, so most of the world doesn't even know it exists.

For a start, it can only infect Macs running OS X 1.2.5 or 1.2.6 (it's possible that 10.2.7 could be infected as well, although we haven't heard about infections from any G5 owners yet). So out of 25-30 million Mac users, maybe 7-8 million tops are using the right version of OS X.

Then they have to be using Safari 1.0 and visit a site displaying affiliate ads for Although these ads are presented as linking to a hot new mail order company specializing on OS X, that's just a cover. Their prices are just high enough to keep people from ordering, but the commission rate is enough to get every Mac webmaster interested enough to sign up for the program.

The ads aren't simple animated GIFs; they're JavaScript programs that install an AppleScript on the user's OS X Macintosh. When this AppleScript is run (it autoruns a few minutes after startup), it accesses your Address Book through Mail and sends itself to the first 100 users who have "mac" somewhere in their email address. The email offers recipients a 15% discount on their first order through

That's the clever part. They try to target just Mac users, and when they visit the XGeeks site, they get infected - assuming they're running the right version of OS X and Safari 1.0. And Switchback then propagates itself again, assuming the visitor has Mail configured on their computer.

Considering the size of the OS X installed base, the number of Safari 1.0 downloads, and the number of OS X users who use Mail rather than something else, we estimate that this virus could potentially infect 5,000 to 20,000 users. And it could take months to reach that level, since OS X users don't restart nearly as often as Windows or classic Mac OS users.

It's only a start, but this is the first OS X virus ever, so everyone should try to get their hands on a copy to see what makes it tick. The next X-virus might actually do something malicious. Consider Switchback a proof of concept that almost sorta works.

Of course, with the latest Window worm on the rampage, nobody but the Lite Side staff has even noticed Switchback.

And why is it called Switchback? Because when you read the source code, the first comment calls OS X users to give up their nonconformity and switch back to Microsoft Windows.

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