The multi-platform backdoor malware was disclosed this week by security firm F-Secure. It was originally discovered on a Colombian Transport website, and relies on social engineering to trick users into running a Java Archive file, meaning it is not likely to be a major threat.
However, its cross-platform design is unique. If users grant permission to the Java Archive, the malware will secretly determine whether the user is running a Mac, a Windows PC, or a Linux machine. When running on a Mac, the malware will remotely connect to an IP address through port 8080 to obtain additional code to execute.
Anti-virus maker Sophos said on Wednesday that the new malware has the potential to affect a higher number of people because of its multi-platform strategy. Typically, malware and viruses target Windows PCs, as they represent the overwhelming majority of computers.
"Once it has found out which operating system you are running, the Java class file will download the appropriate flavor of malware, with the intention of opening a backdoor that will give hackers remote access to your computer," explained Graham Cluley, senior technology consultant with Sophos.
On a Mac, the new malware is defined as "Backdoor:OSX/GetShell.A. According to F-Secure, it is a PowerPC binary, which means users running a modern, Intel-based Mac must also have Rosetta installed.
While rare, cross-platform malware attacks are not unheard of. In 2010, a Trojan known as "trojan.osx.boonana.a" was a Java-based exploit that affected both Macs running OS X, as well as Windows PCs.
As Apple's Mac platform has grown in popularity and outpaced the PC market as a whole, the OS X platform has become a bigger target for hackers. Last month, Apple opted to tone down promotional language on its website that once claimed the Mac "doesn't get PC viruses." Apple's website now says that OS X is "built to be safe."
That change was made just a few months after more than 600,000 Macs were estimated to have been infected by a trojan horse named "Flashback." More than half of the Macs believed to be infected by the botnet were found in the U.S. alone before Apple aggressively released a series of software updates to quash the malware.