Windows can read (but not write) to the HFS (Mac) partition, so the virus/malware can also.
If you have a big fat text file with your credit card number in it, then it can be read.
U R right that the virus will not run if you are booted into OSX.
It is also theoretically possible that the virus can have HFS+ drivers inside it and write to the Mac side anyway, but in practice that is not likely.
In any Windows system, in Device Manager you can right click the Mac "disk drive" and disable/enable it.
In Windows 7 Pro or higher you can right click Offline/Online it with Disk Management.
When disabled or offline, the data is invisible to Windows OS and virus.
To prevent a remote user from access, in Advanced System Settings->Remote Tab, you will see that by default your system can be controlled remotely unless you change it. There are various Remote Services, Firewall settings and User account settings that would have to be enabled/disabled to make it possible as well.
You should have Microsoft Security Essentials ( http://www.microsoft.com/download/en/details.aspx?id=5201 ) as your only anti virus software. I just removed a "Win 7 Antivirus 2012" from friend's Toshiba computer. You'll find more about it with inet search. She was using AVG. The 2012 would not allow access to task manager, explorer, internet anything. I downloaded M. Sec. Ess. to my Mac flash USB drive, and installed it to her PC in Safe mode boot. It got rid of Win 7 AV. Although I had uninstalled AVG, M. Sec. Ess. got rid of remainders of it also.
Microsoft Security Essentials shoud be a part of any Windows installation, (not an option). If some obsolete U.S. Congress unbundling law is preventing this, then maybe Apple could include it as part of BootCamp. For example, OEM supplier HP includes Norton free for x months.
Not a bad idea: Hello Apple, are you listening?
Thanks for this v. informative posting. I am running Windows 7 and MS Office 2010 in a Bootcamp partition on my MacBook Pro. Based on my research thus far, I am going to install MS Sec. Essentials in the Windows partition. Two .exe files are avaialble for download at the link above, those being:
Do I presume correctly that the first is what I want if I've installed 64 bit Windows?
Actually, now that I'm seeing I have discs for both 64 and 32 bit Windows, I realize I don't remember which I installed. How does one verify that?
To see OS (System Type) key msinfo32 into Start Menu search box. More info to browse here.
Relating to your 64 vs 32 Bit option, if you have more memory than can be addressed in a 32bit OS instruction set, you want
to use 64 Bit only.
This is what Msinfo32 shows in my Mac Pro case:
Installed Physical Memory (RAM) 10.0 GB
Total Physical Memory 9.99 GB
Available Physical Memory 8.80 GB
Total Virtual Memory 20.0 GB
Available Virtual Memory 18.7 GB
Page File Space 9.99 GB
In a 32 Bit OS, it would only be able to address ~3GB of memory. See more here for Windows 7 OS
To see and limit what programs run at start-up, key msconfig and click on found object. I limit this list to only Boot Camp and Microsoft Security Client. If you are syncing to Apple devices, you may want to leave those items checked.