I know zero about Linux.
Is it possible to embed a virus in this case WIN32:vitro inside a Linux iso in this case Knoppix?
Because my antivirus flagged a file on the USB stick after using Rufus to make a USB stick Knoppix
bootable image under the isolinux map as being contaminated?
I thought Win virus didnt work on Linux (perhaps a displaced assumption).
It is, of course, possible. When scanning, virus detection is done based on the contents of a file, not the behavior of a program in memory. A file is a file across any operating system or storage medium.
This thread (which is very recent) seems to suggest that the detection of this virus in a Knoppix ISO is a false detection. Even if the virus were really present in the ISO and you installed and used the operating system, it's not likely that it would damage the Knoppix OS installation.