The author of the malware downloaded the original/trial versions of each program and introduced a copy of the malicious binary into the packages. Users who then downloaded and installed the applications from the torrent download would become infected. It is estimated that so far thousands of people have downloaded the malicious torrent files.

So, Mac users be aware of which files you download and according to Symantec “Users are advised to install Norton Internet Security for Macintosh” !!

Sources: ZDNet, The Register