# Is CCleaner Safe to Use on Windows?

The current CCleaner from its official site is a legitimate program and not malware, so in that sense it is safe. The reason people keep asking comes down to a few real incidents, plus features you can use badly: its 2017 build was hijacked, Microsoft Defender flagged its free installer in 2020 for offering other software, and its registry cleaner is something Microsoft does not support. If you use it, install it carefully, skip the registry cleaner, and read what it selects.

## What actually happened

| Year | What happened | What it means today |
| --- | --- | --- |
| 2017 | [CCleaner 5.33 shipped with a backdoor](https://blog.talosintelligence.com/avast-distributes-malware/) from the official servers between August 15 and September 12. The installer carried a valid signature. | Attackers likely got in before release. It was fixed long ago, but it is why the name still comes up. |
| 2018 | Reports said **Active Monitoring** came back on by itself in one release, and that the data collection setting needed better control. Piriform said the feature did not report data, then changed it. | Check its data settings yourself. |
| 2019 | Avast disclosed a [second attempt](https://en.wikipedia.org/wiki/CCleaner) to insert malware in releases, which it said failed. | No infected release resulted, according to Avast. |
| 2020 | [Microsoft Defender flagged the free installer](https://www.bleepingcomputer.com/news/microsoft/microsoft-now-detects-ccleaner-as-a-potentially-unwanted-application/) as a potentially unwanted application, because Microsoft detects software that offers to install software from another developer. Piriform called it a false positive, and [Wikipedia](https://en.wikipedia.org/wiki/CCleaner) records that it later made the offers optional. | Read each installer screen. |

Piriform, the developer, was bought by Avast in 2017, and Avast is now part of Gen Digital.

## The registry cleaner is the part to skip

Microsoft [has stated](https://www.bleepingcomputer.com/news/microsoft/microsoft-now-detects-ccleaner-as-a-potentially-unwanted-application/) that it does not support registry cleaners. There is also little to gain, because removing unused entries does not make a PC measurably faster. [Registry cleaning on Windows](/windows/blog/windows-registry-cleaning) goes into why.

A long list of "issues" does not mean your PC has a problem. It means the scan found entries it can remove.

## How to use CCleaner safely

1. Download from the official site. Do not take copies from download portals.
2. Use a custom install and read every screen, especially on the free edition.
3. Read the default selections. Removing cookies signs you out of sites, and removing history loses it.
4. Skip **Registry**, and skip any driver updater. Windows Update or your PC maker's tool are the safer routes for drivers.
5. Look through the app's settings for data collection and monitoring, and turn off what you do not want.
6. Do not run it on a schedule out of habit. Caches rebuild, so routine clearing makes things slower. [This guide](/windows/blog/windows-cache-cleanup) says when clearing is worthwhile.

## Do you need it at all

Windows already has much of this. **Settings › System › Storage** covers temporary files and Storage Sense, and Microsoft also offers [PC Manager](/windows/blog/microsoft-pc-manager-review) for free. Before adding a cleaner, ask whether you have a real disk space problem, and if the actual issue is speed, [find the cause first](/windows/blog/why-is-my-pc-so-slow).

If you are looking for something else, [CCleaner alternatives](/windows/blog/ccleaner-alternatives-windows) goes through the options by job.

## Where Mole fits

[Mole for Windows](/windows) has no general registry cleaner, only removing entries left by apps you uninstalled, after backing them up. It has no bundled offers and no driver updater. **Clean** shows a review list first, with categories you can read and untick. It also goes beyond cleaning into uninstalling with a leftover review, a disk map and a live status page. It is a paid one-time purchase, so if Storage Sense already keeps your disk in shape, you do not need it.

## FAQ

### Is CCleaner malware?

No. The 2017 incident was a hijacked release that was fixed. The current version from the official site is a legitimate program.

### Why does Windows warn about CCleaner?

In 2020 Microsoft Defender began flagging the free installer as a potentially unwanted application because it offered other software. Piriform later made those offers optional. If you get a warning now, read what it names before going on.

### Is CCleaner's registry cleaner safe?

Microsoft says it does not support registry cleaners, and there is little to gain from one. Skip that feature.

### Is CCleaner free?

Yes, for home use. CCleaner Free covers one PC, while Professional and Professional Plus are yearly subscriptions. Its site lists what each one includes and the current prices.

### Should I uninstall CCleaner?

Not necessarily. If you use it deliberately and read what it selects, keep it. If you installed it years ago and do not remember why, Windows' own tools probably cover what you need.


Canonical: https://mole.fit/windows/blog/is-ccleaner-safe