System and Security settings within the Control Panel
Jason Fitzpatrick / How-To Geek
CCleaner is a safe option for cleaning unwanted files from your Windows PC. Following the software getting hacked in 2017, Avast made the changes needed to help ensure the same doesn't happen again.

After being the go-to Windows system cleaner for many years, CCleaner hit a very rocky patch that started with the discovery of a hack in 2017 and continued with data collection concerns just a short time later. But are those troubled times behind it, and is CCleaner safe for Windows now?

What Is CCleaner?

CCleaner is a system cleanup utility, initially created for Windows by Piriform Software all the way back in 2004. Its core function is to safely remove unwanted files from your computer that have been left behind by other software.

performing a cleaning scan in CCleaner

It also included registry, cookie, cache, and recycle bin cleaning tools and, more recently, added PC performance boost tools and a driver updater, among several others. It has been downloaded billions of times and regularly featured in lists of essential PC software for over a decade.

It could be easy to assume the C in the name (C Cleaner) refers to the C:/ drive where the Windows OS files are commonly installed, or even the word “Computer.” But it actually originates from “Crap.” Yep, the software was launched in 2004 as Crap Cleaner.

Piriform Software and CCleaner were bought by antivirus software giant Avast in 2017. Unfortunately, that was very shortly before all the trouble started.

What Is the CCleaner Hack?

In late 2017, security researchers from the Cisco Talos group reported that version 5.33 of 32-bit CCleaner contained a virus delivery system. Downloading that version of the software, even from the official website, also meant you would be downloading code that could infect your PC.

It was thought that hackers compromised the CCleaner software development environment, which allowed them to inject their malicious code into the signed and certified version after it had been previously checked for such infections.

To its credit, Avast reacted quickly and updated users to a virus-free version 5.34. But considering that CCleaner downloads numbered in the millions per week, it is unsurprising that more than two million machines were affected. Shortly afterward, the 64-bit version was also found to have been breached, but this attack was targeted at tech companies, not home users.

Is CCleaner Safe to Use Now?

Despite the hack of 2017, CCleaner can now be considered safe to use. There have been no other successful hacks or breaches in the years since. Avast did reveal that an attempt was made in 2019 but was prevented before any software could be infected.

As the app is owned by one of the best-known antivirus companies in the world, it is safe to assume that some pretty robust security measures are in place. In fact, Avast completely rebuilt the software using a new infrastructure to help avoid things like the 2017 hack.

CCleaner suffered a bit of a reputational blip in 2018, but that was more to do with forcing updates on users and nothing to do with software security. In that instance, the setting to disable automatic updates was reverting to allow them without user input. It also defaulted to allow data to be collected. This has since been fixed.

the fixed update settings in CCleaner

Another commonly asked question is: “Is the CCleaner Registry Cleaner safe?” The answer to this is also yes, and using the Registry Cleaner tool is unlikely to harm your computer. But we generally don’t think you need to run a Registry Cleaner.

Is CCleaner Good, and Are There Alternatives?

Since being bought by Avast, the free version of CCleaner has become a bit eager for users’ attention and stays open in the background once it has been started. But if you remember to exit the app to avoid the prompts to upgrade to the Pro version, those problems are manageable.

Windows users can still see some benefits of using CCleaner to keep their system free from unwanted files, cookies, and perhaps even some out-of-date Registry entries. It is relatively easy to use, and freeing up some storage space or decluttering your PC is quick and painless.

Several CCleaner alternatives are available that are as good or better than the Piriform/Avast cleaner. These include Glary Utilities, BleachBit, and Wise Disk Cleaner, among a handful of others. Some computer manufacturers even pre-install their own PC cleaning utilities, meaning you might not need to install any extra software to do the job.

the glary utilities interface

Should I Use CCleaner on Windows?

CCleaner was and still is a useful tool for keeping your Windows PC free from unwanted files and various bits of browser detritus. If you use the Pro version of the software, the driver updater can also be a handy feature. And as we have explored, the app is now safe to use if that’s what is stopping you from downloading CCleaner.

That said, the cleanup tools built into Windows 10 and Windows 11 have been greatly improved since CCleaner was first released. There is less need for a stand-alone tool when you can find many of the same file-cleaning features in Windows Settings.

Microsoft also seems to be working on its own system cleaner app called PC Manager, which combines many of the built-in Windows tools and has a very user-friendly interface. It certainly makes sense for Windows users to take advantage of the included tools before installing yet another app.

RELATED: 10 Spring Cleaning Tips for Your Windows PC

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Russ is a freelance writer who specializes in writing about technology. He loves exploring and figuring out how complex things work, and sharing that knowledge with others, something he has been doing online and in print for more than 15 years. When not writing for How-To Geek, Russ can usually be found planning his first novel or taking something apart to see how it works.
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