How to Completely Remove CCleaner Malware from Your PC (2026 Guide)

CCleaner, the popular Windows performance optimization tool with over 2.5 billion downloads, has a troubled history of spreading malware to its users‘ PCs. The program, originally developed by Piriform and acquired by antivirus company Avast in 2017, was compromised in major hacking incidents in 2017, 2019, and again in 2021.

The malicious CCleaner versions known to be infected with malware include:

According to Avast, the 2017 breach affected 2.27 million users who downloaded the 32-bit CCleaner version 5.33.6162 or CCleaner Cloud version 1.07.3191 between August 15 and September 12, 2017. The malware collected system information and transmitted it to a remote server, but Avast said there was no evidence that consumer data was stolen.

However, the attackers were able to compromise high-profile technology companies by targeting CCleaner users within their organizations. Researchers at Cisco Talos found that the hackers attempted to infiltrate at least 20 firms, including Intel, Google, Microsoft, Akamai, Samsung, Sony, HTC, Linksys, D-Link and Cisco itself.

Timeline of CCleaner malware incidents (Source: CPO Magazine)

The more recent attack in 2021 involved hackers replacing the legitimate CCleaner.exe file on Avast‘s download servers with a malicious one, in a sophisticated "supply chain" attack. Users who downloaded CCleaner between July 12 and July 15, 2021 may have received a version equipped with malware designed to steal confidential information and mine cryptocurrency on infected PCs.

Signs Your PC May Be Infected with CCleaner Malware

How do you know if your system has fallen victim to a malicious CCleaner version? Here are some red flags that could indicate your PC is compromised:

• Performance issues: Your computer has suddenly become much slower and less responsive than usual.
• Suspicious network activity: You notice strange connections or increased traffic in your firewall logs or network monitor.
• Antivirus alerts: Your security software has started detecting threats related to CCleaner.
• Altered CCleaner appearance: The CCleaner interface looks different than you remember, with new options or suspicious changes.

If you suspect an infection, don‘t ignore it – follow these steps to clean up your system and protect your data and identity.

Step-by-Step CCleaner Malware Removal

1. Uninstall the infected CCleaner version

First, you need to remove the compromised version of CCleaner from your computer entirely:

1. Open the Windows Control Panel
2. Go to "Programs and Features" or "Apps and Features"
3. Find the entry for CCleaner and click "Uninstall"
4. Follow the uninstallation wizard to remove the program

If you‘re not sure which CCleaner version you have, open the app and look in the top-left corner, or click Help > About. If the version matches any of those listed in the table above, remove it.

2. Run complete antivirus scans

Next, it‘s crucial to scan your entire system for malware that may have been installed by the malicious CCleaner. Use the antivirus software active on your PC, or if you don‘t have one, install a reliable solution from a reputable vendor like Bitdefender, Kaspersky, Norton, or Malwarebytes.

Run a full system scan, not just a quick scan – this may take a couple hours but it‘s important to be thorough. Have your antivirus quarantine and delete any malicious files or programs it detects. To be extra safe, consider running scans with a couple different antivirus scanners.

3. Check your web browsers

Open Chrome, Firefox, Edge, and any other browsers you regularly use. Go through the list of extensions and remove any that you don‘t recognize installing – they may be malicious plugins added by the CCleaner malware.

Then reset each browser back to its default settings. This will clear out any malicious alterations that may have been made, such as changing your homepage, search engine, or privacy settings.

In Chrome: Settings > Advanced > Reset settings
In Firefox: Help > Troubleshooting Information > Refresh Firefox
In Edge: Settings > Reset settings

4. Change all your passwords

Unfortunately, some of the CCleaner malware has been designed to steal information like saved passwords. That means any accounts you‘ve logged into on your PC could be compromised.

To be safe, you should change the passwords on all your online accounts, especially sensitive ones like online banking, email, and cloud storage. A password manager like Dashlane, LastPass or 1Password can help you generate strong, unique passwords and store them securely.

Enable two-factor authentication (2FA) wherever possible for an extra layer of security. This requires a code from your phone or an authenticator app when signing in.

5. Monitor your finances

In the days and weeks after cleaning the CCleaner malware from your system, keep an eye out for any suspicious activity on your financial accounts and credit reports. Look for transactions you don‘t recognize and alert your bank or credit card company right away.

Consider placing a fraud alert on your credit reports, which will make it harder for criminals to open new accounts in your name. You‘re also entitled to one free credit report per year from each of the three major credit bureaus – Equifax, Experian, and TransUnion.

Avoiding CCleaner Malware in the Future

While Avast says it has increased security measures since the breaches, many users remain wary of CCleaner given its history of spreading malware. The safest option is to avoid the program entirely and find alternatives.

However, if you do decide to use CCleaner, follow these best practices to lower your risk:

• Only download from the official site: Always get CCleaner from ccleaner.com or Avast.com, never from third-party download sites that often bundle malware.

• Verify the digital signature: CCleaner releases are digitally signed by Piriform. To check the signature in Windows, right-click the installer, select Properties, and look under Digital Signatures.

• Keep it updated: Install any available CCleaner updates right away to patch security holes. The same goes for your operating system and other software.

• Use trusted antivirus protection: Reliable real-time malware detection can stop malicious software before it harms your system. Our top picks include Bitdefender Total Security, Norton 360 Deluxe, and Kaspersky Internet Security.

According to a 2021 survey by Propeller Insights, 84% of CCleaner users reported being very concerned about the malware incidents, and 64% said they would seek an alternative program. Only 5% said they completely trust CCleaner after the hacks.

Fortunately, there are highly rated tools that can replace CCleaner‘s functionality without the same security risks. Alternatives worth considering include System Ninja, BleachBit, Glary Utilities, and Iolo System Mechanic.

The Bottom Line

CCleaner‘s repeated malware incidents have understandably shaken trust in the program. They demonstrate the importance of caution when using system utility tools, which often require high levels of access and privileges.

"The CCleaner attacks show that even the most popular consumer applications can be compromised," says Simon Migliano, Head of Research at Top10VPN. "Hackers increasingly use this ‘supply chain‘ method to smuggle malware into networks via trusted programs."

"All software tools carry some risks, but users can stay safer by sticking to well-known, reputable programs from the official source," Migliano advises. "Don‘t click on ads or email attachments claiming your PC needs cleaning. And keep your software and antivirus updated to protect against the latest threats."

If your PC has been hit with CCleaner malware, don‘t panic. Follow the removal steps above carefully and you should be able to eliminate the infection. However, prevention is always better than cleanup, so consider switching to an alternative tool to optimize your system safely.