Microsoft has classified CCleaner, a popular PC optimization tool, as a 'potentially unwanted application'

It became clear that Microsoft's standard anti-virus function, Microsoft Defender Antivirus, detected CCleaner, a famous PC optimization tool, as ' Potentially Unwanted Application: Potentially Unwanted Application (PUA) '. If you have PUA protection enabled in Microsoft Defender Antivirus, you will be warned when you try to install the free and 14-day trial versions of CCleaner.

PUA:Win32/CCleaner threat description-Microsoft Security Intelligence

CCleaner is a PC cleaning and optimization tool that efficiently deletes unnecessary temporary files, programs, accumulated history, etc. on the hard disk. It supports more than 30 languages, including Japanese, and has a popularity of being downloaded more than 2.5 billion times , but since the developer Piriform was acquired by Avast Software in 2017, CCleaner has several Has caused problems.

In September 2017, it was revealed that the CCleaner legitimate file was distributed from a legitimate download server with an executable file containing malware mixed in. It is reported that this malware contamination problem was aimed at targeted attacks targeting large companies such as Intel, Sony, and Microsoft.

CCleaner's malware contamination problem turned out to be a targeted attack aimed at large companies such as Intel, Sony, Microsoft-GIGAZINE

On July 29, 2020, Microsoft announced on its official Microsoft Security Intelligence that the free version of CCleaner would be classified as a 'Potentially Unwanted Application: Potentially Unwanted Application (PUA).' Microsoft has long blamed third-party registry cleaners, but this time it classified CCleaner as a PUA because it bundled other applications with the free CCleaner distribution.

Microsoft has pointed out that CCleaner's free and 14-day trial installers are bundled with applications that are not directly related to the way CCleaner works. ``The bundled application itself is legal, but bundling products from other providers in particular can cause unexpected software activity and adversely affect the user experience,'' he said, protecting users from this issue. For that reason, I explained that I classified CCleaner into PUA.

The PUA-classified CCleaner installers include those that bundle Google Chrome, Google Toolbar, Avast Free Antivirus, AVG Antivirus Free and more. Although the CCleaner installer provides the option not to install these applications together, some users are at risk of accidentally installing these applications. Please note that the paid CCleaner installer is not classified as PUA as it does not bundle any third party applications.

A CCleaner spokeswoman said, 'We are working with Microsoft to understand why CCleaner was detected as a PUA. We suspect this is in a bundle and we are addressing this issue. I believe that you can prevent the product from being flagged.'