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CCleaner
Suite of utilities for cleaning disk and operating system environment

CCleaner , developed by Piriform Software, is a utility used to clean potentially unwanted files and invalid Windows Registry entries from a computer. It is one of the longest-established system cleaners, first launched in 2004. It was originally developed for Microsoft Windows only, but in 2012, a macOS version was released. An Android version was released in 2014, and an iOS version was released nine years later.

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Features

CCleaner can delete potentially unwanted files left by certain programs, including Microsoft Edge, Internet Explorer, Firefox, Google Chrome, Opera, Safari, Windows Media Player, eMule, Google Toolbar, Netscape, Microsoft Office, Nero, Adobe Acrobat, McAfee, Adobe Flash Player, Sun Java, WinRAR, WinAce, WinZip and GIMP5 along with browsing history, cookies, recycle bin, memory dumps, file fragments, log files, system caches, application data, autocomplete form history, and various other data.6 The program includes a registry cleaner to locate and correct problems in the Windows registry, such as missing references to shared DLLs, unused registration entries for file extensions, and missing references to application paths.7 CCleaner 2.27 and later can wipe the MFT free space of a drive, or the entire drive.

CCleaner can uninstall programs or modify the list of programs that execute on startup.8 Since version 2.19, CCleaner can delete Windows System Restore points. CCleaner can also automatically update installed programs and computer drivers.910

Piriform also distributes a web browser called CCleaner Browser, included as an optional add-on included within the CCleaner installer. The browser, built on Google's free and open-source project Chromium, includes built-in ad blocking and anti-tracking features. The browser is only available for Microsoft Windows.1112 The browser is identical to Avast Secure Browser, which is also owned by Piriform's parent company, Gen Digital.13

History

CCleaner was first launched in 2004 for Microsoft Windows.14 It remained a Windows-only utility until 2012. On 2 June 2011, Piriform announced a public beta test program for CCleaner for Mac.15 The Mac version graduated to the test stage on 30 January 2012.16

A commercial Network Edition was also introduced. Piriform released CCleaner for Android in 2014.17 Nine years later, the app was released for iOS via the Apple App Store.18

Critical reception

CNET editors gave the application a rating of 5/5 stars, calling it a 'must-have tool'. It was awarded Editor's Choice Award in April 2009 by CNET.19 In 2016 Piriform announced 2 billion CCleaner downloads worldwide.20 In January 2014 it had been the most popular software on FileHippo for more than a year, and had a 5-star editor's rating on download.zone and Softpedia.21 CCleaner has been reviewed by Chip.de,22 TechRadar,23 PC Magazine24 and TechRepublic.25

Data collection

Upon an error in the code, the Active Monitoring component of CCleaner 5.45, which was designed to measure junk levels to trigger cleaning, switched back on again. Piriform recognized this error and confirmed to users that the Active Monitoring feature did not report data. It then changed Active Monitoring to the more accurate title of 'Smart Cleaning'. After criticism later versions allowed data collection to be controlled separately by the user, although some data collection, such as OS and language, which is necessary for the app to be delivered, is still on by default as outlined in the company's Data Factsheet. Piriform states that the data collection is completely anonymous and is used to improve product quality.26272829

Bundled software

Piriform was acquired by Avast in July 2017. In December 2018, it was reported that users installing CCleaner would also have Avast Antivirus installed without their permission, with TechSpot claiming this arguably made CCleaner no better than the malware it was supposed to defend against. Piriform denied this.30

In July 2020, Microsoft Windows Defender began flagging the free version of CCleaner as a "potentially unwanted application", stating that "while the bundled applications themselves are legitimate, bundling of software, especially products from other providers, can result in unexpected software activity that can negatively impact user experiences."31 Piriform rolled out an update days later and third-party software installation is now optional when installing the program.

Malware infection

After Piriform was acquired by Avast, in September 2017, CCleaner 5.33 was compromised by the incorporation of the Floxif trojan horse into the distributed program that could install a backdoor, enabling remote access to 2.27 million32 machines which had installed CCleaner.3334 Avast insisted that the malware was already in CCleaner version 5.33, prior to the purchase of Piriform. Forty of the infected machines received a second-stage payload that appears to have targeted technology companies Samsung, Sony, Asus, Intel, VMWare, O2, Singtel, Gauselmann, Dyn, Chunghwa and Fujitsu.3536 On 13 September, Piriform released CCleaner 5.34 and CCleaner Cloud 1.07.3191, without the malicious code.37

On 21 October 2019, Avast disclosed a second security breach during which attackers tried again to insert malware inside CCleaner releases. The attempt was unsuccessful.38

See also

References

  1. "CCleaner". 6 June 2004. Archived from the original on 6 June 2004. Retrieved 22 September 2017. https://web.archive.org/web/20040606050048/http://www.ccleaner.com/ ↩

  2. Nakodari (7 September 2009). "10 Lessons Software Developers Should Learn From CCleaner's Success". Addictive Tips. Retrieved 25 May 2016. http://www.addictivetips.com/windows-tips/10-lessons-software-developers-should-learn-from-ccleaner-success/ ↩

  3. "CCleaner – Optimization and Cleaning – Free Download". Ccleaner.com. Archived from the original on 25 January 2018. Retrieved 26 October 2011. https://web.archive.org/web/20180125225342/http://www.ccleaner.com/ccleaner ↩

  4. "CCleaner – Phone Cleaner". App Store Apple. Retrieved 23 June 2025. https://apps.apple.com/in/app/ccleaner-phone-cleaner/id6450901367 ↩

  5. "CCleaner – Features". Official web site. Piriform. Retrieved 3 June 2010. https://www.ccleaner.com/ccleaner/features ↩

  6. "Tuning Windows: Less Bull, More Speed". 20 May 2009. Archived from the original on 16 July 2012. Retrieved 2 June 2009. https://archive.today/20120716142339/http://thecoffeedesk.com/news/index.php/2009/05/20/tuning-windows-less-bull-more-speed/ ↩

  7. "CCleaner – Features". Official web site. Piriform. Retrieved 3 June 2010. https://www.ccleaner.com/ccleaner/features ↩

  8. "Screenshot #5: The Startup Tool". Official web site. Piriform. Archived from the original on 29 October 2010. Retrieved 5 November 2010. https://web.archive.org/web/20101029185638/http://www.piriform.com/ccleaner/screenshots/screen/ccleaner5 ↩

  9. "CCleaner Version History". Official web site. Piriform. 26 March 2013. Retrieved 26 March 2013. https://www.ccleaner.com/ccleaner/version-history ↩

  10. "Screenshot #6: The System Restore tool". Official web site. Piriform. Archived from the original on 2 November 2010. Retrieved 5 November 2010. https://web.archive.org/web/20101102035934/http://www.piriform.com/ccleaner/screenshots/screen/ccleaner6 ↩

  11. "CCleaner Browser". CCleaner. Gen Digital Inc. https://www.ccleaner.com/ccleaner/browser ↩

  12. "What's the best browser on the market? | CCleaner". CCleaner. Gen Digital Inc. https://www.ccleaner.com/ccleaner/best-browser ↩

  13. Venkat. "Piriform launches CCleaner browser, available for download". Techdows. Archived from the original on 4 October 2023. Retrieved 4 February 2025. https://web.archive.org/web/20231004203701/https://techdows.com/2019/06/piriform-launches-ccleaner-browser-available-for-download.html ↩

  14. Nakodari (7 September 2009). "10 Lessons Software Developers Should Learn From CCleaner's Success". Addictive Tips. Retrieved 25 May 2016. http://www.addictivetips.com/windows-tips/10-lessons-software-developers-should-learn-from-ccleaner-success/ ↩

  15. "CCleaner for Mac [Beta] Released". ccleaner.com. 2 June 2011. https://www.ccleaner.com/news/release-announcements/2011/6/2/ccleaner-for-mac-released ↩

  16. "CCleaner for Mac v1.01". ccleaner.com. 30 January 2012. Archived from the original on 20 July 2019. Retrieved 20 July 2019. https://web.archive.org/web/20190720100007/https://www.ccleaner.com/news/release-announcements/2012/1 ↩

  17. Ferri-Benedetti, Fabrizio (18 April 2014). "CCleaner for Android: too little, too late?". Softonic. Retrieved 21 June 2017. https://features.en.softonic.com/ccleaner-for-android ↩

  18. "CCleaner – Phone Cleaner". App Store Apple. Retrieved 23 June 2025. https://apps.apple.com/in/app/ccleaner-phone-cleaner/id6450901367 ↩

  19. Rosenblatt, Seth (28 October 2010). "CCleaner". Download.com. Retrieved 15 May 2011. http://download.cnet.com/CCleaner/ ↩

  20. Piriform, Software (3 November 2016). "Piriform Announces 2 Billion CCleaner Downloads Worldwide" (Press release). PR Newswire. Retrieved 2 October 2018. https://www.prnewswire.com/news-releases/piriform-announces-2-billion-ccleaner-downloads-worldwide-599828561.html ↩

  21. Opris, Elena (7 January 2014). "CCleaner 4 Review". Softpedia.com. Retrieved 31 January 2014. http://www.softpedia.com/get/Security/Secure-cleaning/CCleaner.shtml ↩

  22. "CCleaner". chip.de. Retrieved 21 February 2016. http://www.chip.de/downloads/CCleaner_16317939.html ↩

  23. "Download of the Day: CCleaner". techradar.com. Archived from the original on 2 March 2016. Retrieved 21 February 2016. https://web.archive.org/web/20160302161726/http://www.techradar.com/news/software/applications/download-of-the-day-ccleaner-1274209 ↩

  24. "CCleaner (for Mac ) Review & Rating". pcmag.com. Retrieved 21 February 2016. https://www.pcmag.com/article2/0,2817,2400840,00.asp ↩

  25. "Five Tips For Using CCleaner To Degunk Your System". techrepublic.com. Retrieved 21 February 2016. https://www.techrepublic.com/blog/five-apps/five-tips-for-using-ccleaner-to-degunk-your-system/ ↩

  26. Milena Dimitrova (3 August 2018). "CCleaner v5.45 Introduces Data Collection with No Way to Opt-Out". Sensors Tech Forum. Retrieved 14 October 2018. https://www.engadget.com/2018-08-02-ccleaner-piriform-will-add-data-collection-opt-out-uproar.html?guccounter=1&guce_referrer=aHR0cHM6Ly93d3cuZ29vZ2xlLmNvLnVrLw&guce_referrer_sig=AQAAAKR9dx6F9QiZOavQyBtb1vC_SiwUfDsGtvtSV6c77S1Ae5Ssr96LecDNSl9vwrDor6LI5ZNhv-1UuOf5hm1JknOTUJIO3iiRa5K5LcynwL7cns-BmIOx7I672McEXBQXY4IJg-PjFtv16fBEVpbXj2FaBJgLYWAtCd1LCUcRUeW-/ ↩

  27. "CCleaner v5.46.6652". CCleaner.com. 30 August 2018. Retrieved 14 October 2018. https://www.ccleaner.com/news/release-announcements/2018/8/30/ccleaner-v5466652 ↩

  28. Osborne, Charlie. "CCleaner provokes fury over Active Monitoring, user data collection". ZDNet. Retrieved 28 June 2019. https://www.zdnet.com/article/cc-cleaner-provokes-fury-over-active-monitoring/ ↩

  29. "I'm using CCleaner v5.45. Why is Active Monitoring still on when I have switched it off?". Piriform Support. 8 October 2018. Retrieved 14 October 2018. https://support.piriform.com/hc/en-us/articles/360010631671-I-m-using-CCleaner-v5-45-Why-is-Active-Monitoring-still-on-when-I-have-switched-it-off- ↩

  30. David Matthews (19 December 2018). "CCleaner may be installing Avast anti-virus wüüi,t your permission". TechSpot. Retrieved 20 January 2019. https://www.techspot.com/news/77949-ccleaner-could-install-avast-anti-virus-without-permission.html ↩

  31. "Windows Defender is flagging CCleaner as a Potentially Unwanted Application". TechSpot. 3 August 2020. Retrieved 5 August 2020. https://www.techspot.com/news/86216-windows-defender-flagging-ccleaner-potentially-unwanted-application.html ↩

  32. Warren, Tom (18 September 2017). "Hackers hid malware in CCleaner software". The Verge. https://www.theverge.com/2017/9/18/16325202/ccleaner-hack-malware-security ↩

  33. "CCleanup: A Vast Number of Machines at Risk". blog.talosintelligence.com. 18 September 2017. Retrieved 21 September 2017. http://blog.talosintelligence.com/2017/09/avast-distributes-malware.html ↩

  34. "Hackers compromised free CCleaner software, Avast's Piriform says". Reuters. 18 September 2017. Retrieved 22 September 2017. https://www.reuters.com/article/us-security-avast/hackers-compromised-ccleaner-free-software-avasts-piriform-says-idUSKCN1BT0R9 ↩

  35. Dan Goodin (25 September 2017). "CCleaner backdoor infecting millions delivered mystery payload to 40 PCs". Ars Technica. https://arstechnica.com/information-technology/2017/09/ccleaner-backdoor-infecting-millions-delivered-mystery-payload-to-40-pcs/ ↩

  36. "Foreign Economic Espionage in Cyberspace" (PDF). CIA. 24 July 2018. https://www.dni.gov/files/NCSC/documents/news/20180724-economic-espionage-pub.pdf ↩

  37. Wilson, Jeffrey L.; Rubenking, Neil J. (19 September 2017). "CCleaner Professional Plus". PC Magazine. https://www.pcmag.com/review/351824/ccleaner-professional-plus ↩

  38. Cimpanu, Catalin. "Avast says hackers breached internal network through compromised VPN profile". ZDNet. Retrieved 21 October 2019. https://www.zdnet.com/article/avast-says-hackers-breached-internal-network-through-compromised-vpn-profile/ ↩