I download virtual box from http://www.modern.ie/en-US/virtualization-tools#downloads and extracted it. When I tried to run ova file, I couldn't.
$ sudo ./"IE11 - Win8.1.ova" ./IE11 - Win8.1.ova: ./IE11 - Win8.1.ova: cannot execute binary file $ ./"IE11 - Win8.1.ova" -bash: ./IE11 - Win8.1.ova: cannot execute binary file $ ls -l "IE11 - Win8.1.ova" -rwx------ 1 alex staff 3834711040 Mar 28 15:02 IE11 - Win8.1.ova
The same failure from Finder, it said
There is no application set to open the document “IE11 - Win8.1.ova”.