1.4 Million Users Install Chrome Extensions That Inject Code Into eCommerce Sites

ndpoint security company McAfee warns of five malicious Chrome extensions designed to track users’ browsing activity and inject code into ecommerce platforms.

With a total install base of over 1.4 million, the extensions can modify cookies on ecommerce websites so that their creator receives affiliate payments for the purchased items, without the victim’s knowledge.

The five malicious extensions help users watch Netflix shows together (Netflix Party and Netflix Party 2, with a combined install base of 1.1 million), enable them to track online prices and coupons (FlipShope – Price Tracker Extension and AutoBuy Flash Sales, with 100,000 installs), and capture screenshots (Full Page Screenshot Capture – Screenshotting, with 200,000 installs).

McAfee’s analysis of the extensions has revealed that the user tracking and code injection behavior resides in a script named ‘b0.js’, which contains many other functions as well.

The extensions subscribe to events triggered when the user accesses a new URL in a tab, so they can send tracking data to the creator’s server (at langhort.com), which checks if the user navigates to a site for which an affiliate ID exists.

Based on the response received from the server, the extension can inject into the website a URL as an iframe and a cookie containing the affiliate ID of the extension developer, who receives a commission for any purchase the user makes on the target website.

According to McAfee, this mechanism essentially allows the extensions to “add any cookie to any website”, as they had permissions to do so.

The security firm also noticed that the extensions contained an evasion mechanism: they checked whether 15 days had passed since installation before beginning the malicious behavior.

The extensions are still available in the Chrome Web Store at the time of writing.

McAfee encourages users to thoroughly check extensions before installing them, even if they already have a large install base, and to pay close attention to the permissions the extensions ask for, such as the permission to run on any website the user visits.

Related: N Korean APT Uses Browser Extension to Steal Emails From Foreign Policy, Nuclear Targets

Related: Google Patches Several Chrome Flaws That Can Be Exploited via Malicious Extensions

Related: Chrome Extensions Policy Hits Deceptive Installation Tactics