Developers of the HandBrake DVD-ripping app have issued a warning that attackers inserted malware into copies of the app on one of its download mirror servers. They have shut that server down, but if you downloaded HandBrake between 14:30 UTC 2 May 2017 and 11:00 UTC 6 May 2017, you may have been infected. The HandBrake forum post provides more details on how to see if your Mac is infected and how to remove the infected files if so. If HandBrake’s developers had digitally signed the app, this never would have happened. Apple has also updated XProtect to protect against future downloads of files infected with Trojan OSX.Proton.B.