Google recently removed an app from its Chrome Web Store that looked like Adblock Plus, but the 37,000 people who downloaded it should be on the lookout for a possible data breach.

An anonymous researcher who goes by the name SwiftOnSecurity was among the first to draw attention to the phony extension in a tweet. Though it’s unclear whether the developer behind it was out to cause a data breach, its tactics resemble those of a typical cybercriminal.

Fake Adblock Plus App Puts Users at Risk of Malvertising

According to a blog post from the genuine Adblock Plus, the phony version, which used the exact same name (other than a capital B in AdBlock), was marketed as an app in the Chrome Store as opposed to an extension. There were even reviews of the fake product, TechRadar reported.

According to Engadget, users who downloaded the phony product reported that it has done the opposite of what a real ad blocker is supposed to do: It took over their browsers and opened more ads in multiple tabs. This may not be as bad as causing a data breach, but fraudsters have been known to inject code into online advertisements in a process called malvertising, so users should be wary.

Dangerous Data Breach Potential

As Android Authority pointed out, Adblock Plus has attracted millions of users over the last several years and is arguably one of the most recognized names in the ad blocker category. Google acted quickly to remove the phony version but has yet to explain how its verification procedures failed to recognize it. If something like this can get through, what about a fake app aimed at causing a data breach?

Upon closer inspection, experts noticed that the phony Adblock Plus extension ID used Cyrillic characters. Bleeping Computer suggested that this may have allowed the automated systems in the Chrome Web Store to give the fake extension the green light.

Still, this is at least the second time a bogus version Adblock Plus has gotten into Google’s repository, so additional measures to beef up security may be required. People dislike online ads, but they would dislike a data breach even more.