There’s a new strain of malware that specifically targets OS X.

Virus hunters have discovered a sophisticated botnet targeting Mac OS X computers and using a novel technique to operate. The malware has infected about 18,500 Macs, according to recent statistical analysis.

The Mac malware, called iWorm, uses a complex multi-purpose backdoor, through which criminals can issue commands that get the malicious program to carry out a wide range of instructions on the infected Macs.

According to researchers, the backdoor makes extensive use of encryption in its routes. It is capable of discovering what other software is installed on the infected machine and sending out information about it (operating system), opening a port on it, downloading additional files, relaying traffic, and sending a query to a web server to acquire the addresses of the C&C servers, essentially turning your Mac into a zombie.

To see if you are infected, go into the Finder and Select Go > Go to Folder…. When the Go to folder sheet appears, enter this folder name:

/Library/Application Support/JavaW

Now click the Go button. If the Finder tells you the folder can’t be found, you should be OK. If the folder is found, you are likely infected and should consider some anti-virus software or a trip to the Apple Store.

The linked article is definitely worth a read. [Hat Tip Stu Mark]