Is it a DXF file with that extension (xxx.dxf)? If so, are you trying to “INSERT”, because that is how it gets into a Fusion 360 drawing.
Drop the file into a post and one of us would be happy to look at it for you.
Another thing you could try to do is to see if it will convert to an SVG file. If it is a virus, I would doubt that a virus could result in conversion to another ‘lifeform’ such as an SVG file. If it can, well that is pretty sneaky.
Now there was someone a few months ago that was having trouble with getting a file to insert into Fusion 360 and after numerous attempts at updates and re-installs of Fusion, finally got it to work. I will try and find that thread.
Here is one that was solved with a new graphics card:
Here is one where the file type was wrong from the source:
Edit: BTW…still not finding the thread I was remembering.