Issue
I just installed Virtual BOX to run linux labs. I am running into the issue, when I download Ubuntu or Kali .ISO or .OVA file extensions these files appear as if they were PDF files - so VM does not recognize them. Any suggestions towards correcting this scenario is appreciated.
Solution
I am not sure about .ova files but you can try downloading the Ubuntu ISO file from here.
Also, are you correctly using the ISO file in Virtual box by going to the VM -> Settings -> Storage and then clicking on the disk icon besides controller, that should open the file explorer and give you the option to add the ISO file.
Answered By - Arcc