We know that a few of our customers sometimes use a product known as CCleaner to clean junk out of their file systems on client machines and perhaps even their servers. Apparently, some malware was planted in an official release version of the CCleaner software which some people may have downloaded.
You may want to review the following article from PC World that describes the problem and how it can be resolved. https://www.pcworld.com/article/3225407/security/ccleaner-downloads-infected-malware.html
Click on the link above to review the information.