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All five extensions discovered by McAfee behave with the web app manifest (“manifest.json” file), which dictates how the extension should behave on the system, loads a multifunctional script (B0.js) that sends the browsing data to a domain the attackers control (“langhort[.]com”).
The data is delivered through via POST requests each time the user visits a new URL. The info reaching the fraudster includes the URL in base64 form, the user ID, device location (country, city, zip code), and an encoded referral URL. If the visited website matches any entries on a list of websites for which the extension author has an active affiliation, the server responds to B0.js with one of two possible functions. The first one, “Result[‘c’] – passf_url “, orders the script to insert the provided URL (referral link) as an iframe on the visited website.
The second, “Result[‘e’] setCookie”, orders B0.js to modify the cookie or replace it with the provided one if the extension has been granted with the associated permissions to perform this action.