I'm going to start this entry with a mea culpa. To be fair to Symantec, they didn't put out a press release about OSX.Macarena. They answered the questions of a media outlet which contacted them. That particular media outlet deserves the blame for trying to make a mountain out of a molehill—or a news story where there really was not enough information to do anything more than spread fear, uncertainty, and doubt. I am sure that responsible media outlets spreading FUD bugs the rest of you just as much as it bugs me. The underlying problem of whether the mac-o-sphere trusts anti-virus companies not to cry wolf is a whole 'nother issue, and one that will have to be dealt with at the critical point when a virus appears and is a real threat. That's a tough nut to crack.
Today, there is more information on OSX.Macarena, this time from Intego, which, by the way, did send out a press release for their November 6 Security Memo. It's interesting to note that this is not the "Macarena" virus, it's the "Mach Arena" virus. The risk remains very low, but there's more information about the source of the virus, its effects and transmission methods. A wise move on the part of Intego, if you ask me. Information smashes FUD flat.
The upshot is OSX.MachArena only infects only mach-o binaries. In my limited experience, mach-o binaries are generally Terminal related—command line programs, or dynamicly linked libraries of code (my experience with mach-o is very limited so if someone else can explain better what is and is not vulnerable, please feel free to comment). Only mach-o binaries in the same folder as an infected executable can be infected, which severely limits possible outbreaks. PPC and Universal applications are immune.
The virus spreads from a Mac's Windows installation. Users of both BootCamp and Parallels Desktop can be infected. We don't have to warn y'all that if you run Windows on your Mac, you open yourself up to a host of Windows virus and security problems, do we? We didn't think so.
Will makers of Windows virus software (some of which is free) protect against possible infection from the Windows side of the problem? There is a distinct possibility that this could be seen as a "mac-only" problem and thus not worth their time. And will Apple and the various virtualization providers will create technical barriers to virus transmission from Windows installations to their Mac hosts? This is a big open window in a Mac's armor. It might be nice to see some bars and security glass.