One reason behind the steady rise in Apple Macintosh computer usage over the past several years is that Microsoft Windows has been fraught with so much malware, spamware, trojans and viruses, surreptitious keyloggers and identity theft. If your credit card has been used fraudulently without actually being stolen, and you are a Windows user, good chance there is a keylogger lurking on your PC. It’s become a tiresome day-to-day chore to defend your computer from the many thousands of attack vectors a Windows PC faces online. Who wouldn’t want some relief from that huge time-waster? The Macintosh operating system remains still to this day virtually free of computer virus infections, and most Mac users do not bother running any kind of virus protection software on their Macs at all.

Is your Mac infected?Some say it takes just 20 minutes for a new PC running Windows to get infected once it’s connected to the internet.

That said, the rising popularity of Macs inevitably makes them an increasingly attractive target to attackers. These days trojans are the most likely mode of infection. You know the story of the trojan horse? Something that looks so attractive you gotta have it, but it carries a nasty hidden payload. Trojans are applications downloaded from the internet. They are malware in disguise. You want to avoid getting infected by trojans? Simple — don’t download apps from the internet.

 Flashback

Unfortunately, it’s no longer that simple. A trojan named “Flashback” is the first real threat to Macintosh security. A malicious web site exploits a vulnerability in Java which is used by the Mac OS Safari web browser. If you visit the malicious site, the vulnerability can be used to download the Flashback trojan without your permission. The automated download is what’s made this a real threat to your Mac’s security.

According to anti-virus company Kaspersky Labs the “Flashback” and the related “Flashfake” viruses targeting Macs first appeared back in September 2011, and there are now over 600, 000 Macs infected. And the infection appears to be growing. Kaspersky now has a Flashback Check web site you can use to find out whether your Mac is infected or not.

Apple has come out with two updates to the Java runtime extension that is used by Safari. I recommend that you open your Apple > Software Update… menu now and get these updates. (If it’s been a while since you ran Software Update on your Mac, there may be other security updates there as well.) And if your Mac is already infected

Apple reportedly has it’s own Flashback Removal Tool in the works too, but if the Flashback Check shows you’re already infected you can follow instructions from Finnish security firm F-Secure to manually remove all files associated with this infection.