steeldrivingjon said:
The virus won't know how to deal with the Mac OS X filesystem, so it couldn't do anything to the files. If it mucks with the partition table, or tries to write raw data to the Mac OS X partitions, there might be trouble. I don't know if there's any way to protect from that.
I have no idea what a Windows virus would do to an OS X volume on a firewire drive. I wouldn't be surprised if Windows virii just ignored such things, because they aren't common on Windows machines.
So that might be an option : set up a backup on a firewire disk, or even a RAID mirror.
The safest way to use Windows on an Intel Mac would be to run it inside VMWare or VirtualPC. With those, you can create the Windows volume as a disk image-type thing on your disk. This lets you run Windows in its own sandbox.
Most viruses won't do a &@#%*& thing to an HFS+ partition, as most viruses (as they are today) simply work with the filesystems the OS knows how to read. If you have a piece of software that runs on the Win partition and can read and write HFS+, the virus will be able to affect that. If you have MacOpener running on your Windows partition, MacOpener will probably enable viruses to read and write to your HFS+ partitions, including FireWire partitions (including iPods). However, the virus will not be able to infect your OS X system - i.e., if you get infected with a spambot worm in your Windows system, it won't run on your OS X system, though it might be able to write copies of itself to the HFS+ partition that OS X runs on (if you have MacOpener, that is).
Some viruses can muck with the partition table or write binary data to partitions. There are also BIOS flash viruses, which by altering the firmware on the BIOS would affect the functioning of the hardware regardless of the filesystem or operating system being used They are rare, though, because they take far more in the way of programming skill than the script kiddies and spam kings who write most of the viruses are capable of, and are pointless: they don't give you anything more than a criminal record.
In other words, let's say you had a Macintel system with no HFS+ partitions on its internal drives, a Mac-formatted iPod, and an external FireWire drive with a Windows XP partition on it and with MacOpener installed, and that the firmware (let's say EFI) on the computer enabled bootable FireWire drives and was flashable. Let's say MacOpener for these machines mounts your internal HFS+ partition as your E:\ drive, and your iPod as your F:\ drive. Next, let's say that someone writes a new version of the Win95.CIH virus (aka Chernobyl) that runs under XP and can flash EFI (rather than running only under 95/98/ME and flashing BIOS like the real CIH virus can), and spreads as a worm via an unpatched Windows vulnerability. You now have a very expensive set of paperweights.
Thing is, I am not sure that one could WRITE a version of CIH for XP (it only runs on 9x), or one that could flash EFI. Though Symantec lists CIH as being in the wild, I haven't heard of anyone getting it (or anything like it) for years. Such a virus would require real skill, and would have no use except simple mayhem: no spambots. Such virulent viruses aren't common any more.
See
http://www.sophos.com/virusinfo/articles/cihfive.html for a quick, non-technical discussion of Win95.CIH, see
http://www.theregister.co.uk/2000/09/15/chernobyl_virus_author_faces_3years/ for some more information on the author, and see
http://www.symantec.com/avcenter/venc/data/cih.html for the Symantec description of the virus.
Short answer: if you want to run Windows on your Mac (when it becomes possible) and access your Mac files, use antivirus software and a good firewall product (and proabably it's best to put the machine behind a router of some sort), and patch as soon as patches are available and worry about what software they break later. But don't be terrified of it: the odds that you'll get something that slags your machine, or that affects your OS X partition in any way, are very, very, very low.
These are also good ideas for Macs without Windows. Though I think the contribution of low market share to Mac safety is over-rated (I think there are things about OS X that make it harder to write effective viruses), there are proof-of-concept viruses that demonstrate ways of attacking OS X, and there are likely many thus far undiscovered vulnerabilities in OS X (though I would argue that there are probably far fewer than in Windows). Antivirus software and firewalling are just good sense.
