If recent stories of malware have you fretting, take a deep breath: All is not lost. Apple last week updated the anti-malware definitions in Mac OS X to protect against a recently-discovered Trojan horse that masquerades as a PDF.
The malware, OSX.Revir.A, was uncovered by security researchers last week. Posing as a Chinese-language PDF, the nasty piece of software installs backdoor access to the computer when a user opens the document.
If you're running Snow Leopard or Lion, however, there's good news: The operating system's malware protection system will now detect the threat. That means that if you try to open a file containing OSX.Revir.A, your Mac will warn you that all is not what it seems.
Given the fairly speedy level of Apple's reaction--according to my own system, Apple's update arrived last Friday--it seems that Cupertino has finally gotten its malware protection working in a smooth and speedy fashion. The company added the ability for daily definition updates in May of this year; previously, new definitions came only packaged in the company's periodic Security Updates.
However, that said, Apple has yet to deliver an update that protects against a separate Trojan horse making the rounds, dubbed "Flashback." This malware purports to be an installer for Adobe's Flash Player; upon being run, it sends information about the infected Mac back to a central server.
For the most part, Apple's malware definitions updates occur transparently, but should you want to make sure your Mac has the most current protection available, you can always force a definition update. And, of course, the built-in system isn't license to avoid common sense surfing tips, like making sure you download software from legitimate sources and not clicking on strange links.