Today 1-10-17, while running CCleaner Pro, I got the threat warning from Norton Security (for the first time). Norton blocked "SONAR.cryptlk.AF!g12" in ccleaner64.exe as Serious Threat. Based on Dave's post, I'm going to Allow it.
Win10 Pro 1607; CCleaner Pro 5.25.5902; Norton Security 22.8.1.14.
Thx, ChasBob