Version 5.33 of the CCleaner app offered for download from August 15 to September 12 was modified to include the Floxif malware. The malware collected information such as installed software, a list of running processes, MAC addresses for the first three network interfaces, and MAC addresses. Avast CTO Ondrej Vlcek said the most recent recent versions fixes any issues, as “the only malware to remove is the one embedded in the binary itself”” The malware only ran on 32-bit systems and quit execution if the user was not using administrator account.”
Source: https://www.bleepingcomputer.com/news/security/ccleaner-compromised-to-distribute-malware-for-almost-a-month/