Mac Observer:

A popular video conversion app for Mac has suffered a malware infection on one of its mirror servers. If you downloaded HandBrake between 10:30 a.m. EDT on May 2, 2017 and 7:00 p.m. EDT on May 6, 2017, you should follow these instructions to check your Mac for a new variant of the malware OSX.PROTON. Yes, HandBrake was compromised by malware.

If you didn’t download it during the above times, you have nothing to worry about.