Hi, I'm a Win7-Pro 64bit SP1 urser from the Netherlands, with the setting "Automatically check for updates to Ccleaner" for my (64b) free Ccleaner.
Yesterday (2017-09-20) I got the system-tray notification "New version 535 - install now?", Yes, I did. After a moment, installation was ready, version 535, everything worked, looked fine, no security warnings. Today, all of a sudden my Windows Defender gave an alarm: "The ccsetup533.exe file contains malware (Backdoor:Win32/Floxif); severe threat; remove immediately" (or words like that), with a link to the explication: https://www.microsoft.com/