Protecting USB flash drive against viruses

Question

I got some questions about USB FLash drive protection:

1. I'm using Panda USB Vaccine to protect my Flash drive. As far as I know, Panda's app makes autorun file read-only. Imagine that, my flash drive infected by virus. When I insert this drive to the PC that have no antivirus software, is there any chance that virus will be "turned on" even if it has no autorun file access?

2. How far can go flash drive viruses? For ex, I'm web developer, and I'm carrying XAMPP server in my flash drive. Recently when I insert this drive to PC that has Kaspersky Internet Security, it detected 2 XAMPP files as virus. (I worked on this PC about 10-15 times. But Antivirus detected only yesterday.) It offered me to disinfect or remove. I selected disinfect. And KAV kinda disinfected these files. Is there any chance that virus can get this much deeper or it's just KAV?

3. Is there any portable, free antiviral protection, that will protect my USB drive (NOT PC!!) from being infected?
   Actually, I have Clamwin for PortableApps. But it's only "1 time scanner" (It's not scanning always). I mean, it will not protect if I insert this drive into the computer that has no antivirus software.
   P.S. Lets say there is portable scanner. Imagine that I inserted my flash drive into the PC that already has antiviral software. How about this? Will flash drive's antivirus conflict with PC's?

Solution 1

You can use USB Dummy Protect

Its a small utility for protecting USB drives from viruses. Copy it to USB drive and execute from there. It creates dummy.file file which takes all free space and there is no more space for viruses. To unprotect drive execute this utility again or manually remove dummy.file.

It is not antivirus. You could execute it in virus free environment (at your computer for example). Then when you put your USB drive into computer with viruses most of viruses cannot infect your drive, because there is no room for virus there. Also its useful only if you need to read files from your drive. If you need to write something to it you need free space on USB drive and viruses could use this space too.

Known limitation: wouldn't work if there is more than 4GB free space on FAT drive. Solution: Format your portable drive with NTFS file system.

Solution 2

The simple solution is to not plug USB drives into computers you don't trust and then accept them back in your own machine.

1. I don't know enough about modern day viruses to deduce what they will try. Is it possible to write one that can get round this protection? Yes. Pretty easy actually.

2. That depends how inventive the person who wrote the virus was. There are / have been many viruses that search every drive for any executable they can find and write them selves into it. No windows program that the PC has access to is safe. I've even seen a virus get into RunDLL (a core windows component) which is an impressive feat and a very destructive one.

3. There is a switch on some USB drives to make them read only. But if you want it writable then no, the drive is passive memory and not a computer itself. The computer can write whatever it likes to it. If your computer is infected then the virus can write what it likes too. There's stuff like Panda made to try to trip up a virus but its not fool proof.