Windows 10 turns thumbs down on CCleaner

Windows 10
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For 16 years, CCleaner has been a popular computer system cleaning and optimization tool, known for efficiently removing unwanted files, programs and accumulated digital fragments from users' hard drives.

This week, Microsoft told CCleaner: "You're not wanted any more."

Microsoft Defender (until this May known as Windows Defender) has begun tagging the free version of Avast CCleaner as a PUA—Potentially Unwanted Application.

CCleaner excels at detecting and resolving common computer registry problems such as missing references to shared DLLs, unused registry entries for file extensions, and missing references to association paths.

Microsoft has long scoffed at third-party registry cleaners as potentially causing problems. In this instance, however, the company appears to be focusing on the manner of CCleaner's distribution as part of a multi-program software bundle as its main concern.

"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," according to Microsoft's PUA notice. "To protect Windows users, Microsoft Defender Antivirus detects CCleaner installers that exhibit this behavior as potentially unwanted applications."

The free version of CCleaner is packaged with Google Chrome browser, Google Toolbar, Avast Free Antivirus and AVG Antivirus Free.

Microsoft stated that while users can decline to authorize automatic installation of the bundled programs, some users inadvertently install them anyway. Microsoft said it objects to "misleading or inaccurate claims about files, registry entries, or other items on your PC."

Microsoft Defender warns users of its concerns and then allows users to either halt or proceed with installation.

CCleaner, originally named Crap Cleaner when the small company Piriform released it in 2004, had a sterling reputation through 2017. In the early 2000s, it was earning rave evaluations from reviewers, garnered top scores in tests, was termed a "must-have" tool by leading publications and topped at least one respected list of most popular utilities for more than a year. In 2017, downloaded copies of CCleaner surpassed the 2 billion mark.

But after Piriform was bought out by Avast in 2017, CCleaner and Avast took a few hits.

In 2018, consumers began complaining about unwanted bloatware added to download files, as well as a tremendous number of irritating pop-ads. Then it was discovered that CCleaner incorporated a new component, Active Monitoring, that collected computer data without the consent of the user. The company denied that it exposed the identities of users, but added new options for user control over collection. Data collection remained on by default.

Around the same time, hackers broke into CCleaner, enabling remote access to targeted machines. Avast said the breach occurred before it acquired CCleaner.

And late last year, Avast drew the fury of many users when it was discovered that its free anti-virus program was harvesting browser histories for sale to third parties. Avast said the data was "de-identified" and not traceable to individual users. But a report by PC Magazine and Motherboard, in consultation with privacy experts, determined that timestamp, persistent device IDs and recorded URLs could be used to identify users.

The current PUA warning applies only to the free version of CCleaner. The paid version does not include third-party software, the main source of Microsoft's objections.

A spokesperson for CCleaner stated, "We are in the process of engaging with Microsoft to understand why CCleaner was recently detected as PUA. We surmise the issue appears to be around bundling, and we believe we have addressed this so that our product is now no longer flagged."

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