Alphabet Inc. subsidiary Google (GOOG) is not done with cryptocurrencies yet. 

After banning cryptocurrency-related ads from its platform, the Mountain View company today banned cryptocurrency-mining extensions from Chrome, its popular web browser. (See also: Bitcoin Price Spirals Towards $8,000 After Google Bans Crypto Ads). 

“Until now, Chrome Web Store policy has permitted cryptocurrency mining in extensions as long as it is the extension’s single purpose, and the user is adequately informed about the mining behavior. Unfortunately, approximately 90% of all extensions with mining scripts that developers have attempted to upload to Chrome Web Store have failed to comply with these policies, and have been either rejected or removed from the store,” the company stated in a post announcing the move. Chrome is the world’s most popular desktop web browser with more than a 60 percent share of the overall market.

Google’s crackdown on cryptocurrency-related products and services is not unwarranted. Its app store has become a popular venue for blacklisted crypto apps that steal user data or use the host computer’s CPU for cryptocurrency mining without authorization. 

According to research released earlier this year, Google’s app store had the highest number – 272 - of malicious crypto apps among app stores. The most prominent case of a Chrome extension using CPU power without consent was that of SafeBrowser, an extension that promised to block “annoying” ads but also mined Monero in the background. As Ars Technica reported, the company had earlier released the ESET anti-malware engine to make protect Chrome from apps that inject code as extensions.

To be sure, there are legitimate cryptocurrency mining extensions also available on the Chrome store. Coinhive is the best-known example. Cryptocurrency extensions are also being used as a potential source of revenue by media organizations, which have seen their share of the advertising pie decline.

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