
CCleaner version v5.33.6162 has recently been determined by Piriform to have Malware embedded after a security breach affecting up to 2.27 million users globally.
It is highly recommended that all users check their version of CCleaner and update if necessary. It is imported to note that this only effects the 32bit version of CCleaner and that on 64bit systems although both the 64bit and 32bit version are installed, only the 64bit version is executed.
Malware Bytes has been confirmed to pickup and remove the infection (Nyetya trojan) but it’s still a good idea to check your version (start up CCleaner and look at the top left hand corner).
This comes at an unfortunate time for the product as CCleaner has just been purchased by Avast in July. Despite these set backs CCleaner is still a tool we recommend using and it still makes our Top 5 list of Windows tools and applications
Original post from Piriform
Also see:
https://techcrunch.com/2017/09/18/avast-reckons-ccleaner-malware-infected-2-27m-users/
https://www.cnet.com/au/how-to/ccleaner-was-hacked-heres-what-to-do-next/
https://www.gizmodo.com.au/2017/09/your-copy-of-avasts-pc-cleaner-ccleaner-could-be-full-of-malware-update-now/

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