The researchers of American companyICEBRG security researchers identified four Chrome extensions that contained malicious code. All four extensions were available through the Chrome Web Store.
According to the researchers, the four extensions of Chróme were designed to allow attackers to send malicious commands to programs user browsing in JavaScript. 
Attackers used this feature to perform click fraud by loading a page on the background which contained advertisements.
The names of the four extensions are:
Change HTTP Request Header (ppmibgfeefcglejjlpeihfdimbkfbbnm), Nyoogle – Custom Logo for Google (ginfoagmgomhccdaclfbbbhfjgmphkph), Lite Bookmarks (mpneoicaochhlckfkackiigepakdgapj), and Stickies – Chrome's Post-it Notes (djffibmpaakodnbmcdemmmjmeolcmbae).
Of the four, Nyoogle is still available on the Chróme Web Store, up to now.
Extensions have been down altogether over 500.000 times by Google's browser users. When the ICEBRG researchers detected malicious behavior of addons, they informed the National Center for Internet Security in the Netherlands (NCSC-NL) and US-CERT.
While three of the four extensions were removed directly from the Chrome Web Store, many of Chrome's users are still using them in their browsers.
The company published a detailed report for the malicious behavior of extensions in the hope that users will spend some time controlling their browser and removing malicious extensions from their computers.
