http://virus.wikidot.com/stoned

Assuming it's not a false positive the threat would be if you unknowningly spread it to a DOS system like those used in embedded systems.

keenerb wrote:

I do find it very interesting that Windows Defender maintains virus lists that include such ancient code though...

In the case of actual viruses, I've never actually heard of a situation where they'd be removed from anyone's definitions for being "too old".

keenerb wrote:

What threat, realistically, would an MS-DOS virus from 1991 present to a WIndows 10 PC? I expect the answer to that to be "None."

On a 32-bit version of Windows 10 it could potentially do some damage, depending on what it actually does.

Umm, this virus in question activates when you *boot* from the disk. It has nothing to do with Windows 10. And it overwrites/moves your boot sector. I have no idea what would happen if it does that to a GPT disk, but I'll bet nothing good.

So yeah, if you can still boot from a floppy and you don't have secureboot or some kind of boot sector protection on, it could potentially still do a bunch of damage.

Try it & see what happens if you don't believe me.

I thought UEFI would mitigate old DOS boot sector viruses. I haven't really looked into it though.

keenerb wrote:

I thought UEFI would mitigate old DOS boot sector viruses. I haven't really looked into it though.

You need to do an experiment! 😉

UEFI is immune to older boot sector virusus, there is two boot sectors for UEFI one at the front of the disk, one at the back, if the checksum doesn't match it will unlock the 2nd boot data and copy it back to the front data and boot up normally.

A virus is a virus. Whether or not an old virus is able to affect a modern computer architecture/software is another matter. But it's still a virus nonetheless.