I know it was hacked 3 years ago but... Is it safe now???
Yes, there was a blip where there was an infected version in the past, but that is long gone.
So its gone? Right? CCLEANER is safe to install?
Yes, CCleaner is fine, and the attack 3 years ago wasn't realy anything that affected any home, or small business, user.
Analysis has shown that the trojan was actually highly targeted at 18 large IT corporations - think Microsoft, Intel, Google, Sony, Samsung, etc.
It's now regarded that it was a State (government) Sponsored attempt to steal technology from those companies.
Tthe State that did it had no interest at all in any other users.
The first stage that got widely distributed did nothing except to check if it was on a machine at one of those companies.
If it wasn't at one of those companies then it did nothing else at all.
If it was at one of those companies then it 'phoned home' and tried to download a second stage, only 40 machines at those big companies worldwide actualy got that second stage delivered.
Just 40 machines worldwide shows how highly specific it was.
You can see a list of the companies that actually got the second stage (and more technical details) in this article from 2017:
https://blog.avast.com/additional-information-regarding-the-recent-ccleaner-apt-security-incident
If you do somehow manage to get a copy of the CCleaner version installer that was affected three years ago (which won't be easy to get hold of) then any Antivirus programme will recognise and quarantine it even though it is no longer regarded as any threat for a regular user.