Investigators recommend restoring systems to backed-up versions dating before August 15, when the first infected tools were released. The infected version of CCleaner should be uninstalled and antivirus scans initiated to ensure the system is clean.

Why you should not use CCleaner?

CCleaner just became worse. The popular system-cleaning tool now always runs in the background, nagging you and reporting anonymous data back to the company's servers. We don't recommend you upgrade to CCleaner 5.45. ... CCleaner has even been hacked to contain malware.

Is CCleaner Safe 2021?

No, CCleaner is a legitimate app for Windows, macOS, and Android. Piriform originally developed it, and Avast now controls it. In fact, it has been around since 2004. Sadly, many people have erroneously thought of it as malware after being the subject of two cyber attacks since 2017.