Snowden’s Favorite Ad Blocker Can Now Automatically Detect New Tracking Scripts

Ghostery just escalated the ad blocking arms race.
Image: Ghostery/Shutterstock / Composition: Louise Matsakis

Last month, I reported on a Princeton University study that detailed the existence of “session replay scripts,” powerful tracking tools that can record your every keystroke. The study found they were being deployed on hundreds of the world’s most popular websites and consumers generally couldn’t protect themselves fully using ad blockers.

Soon after the study came out, a number of ad-blocking tools did add the scripts to their block lists, and now users can stop them with tools like AdBlock Plus. But what if an ad blocker was able to detect new trackers on its own, and could continuously learn to stop them?


Ghostery 8, the latest edition of Edward Snowden’s recommended ad blocker, is now using artificial intelligence to recognize new tracking scripts as it encounters them. Most ad blockers work by comparing the scripts they find on a website to a predetermined list they have been instructed to block. In other words, they’re unable to block anything they’ve never seen before.

Ghostery's technology has the potential to disrupt the online advertising industry, which has historically relied on tweaking its code to try and evade ad blockers. Ghostery is essentially automating what was once a cat and mouse game played by humans.

“The tracker ecosystem is always evolving, with new trackers being added almost daily,” Jeremy Tillman, Ghostery’s director of product management, told me in an email. “There will always be a long tail of trackers that we simply don’t know about yet. Ghostery isn’t alone in this; all ad blockers and privacy tools that take a list approach suffer these same limitations.”

Beginning Wednesday, Ghostery will be able to detect new trackers in real time, even if they’re not included in its database. The technology will be able to tell if trackers are collecting personal information about a user. If they are, Ghostery “overwrites this data so that the tracker sends generic placeholder data rather than something that is personally identifiable,” Tillman told me. The tech was developed by Cliqz, a privacy-focused browser that acquired Ghostery earlier this year.


Ghostery’s new technology might sound fancy, but it’s actually intended to make ad blocking more intuitive for the average user. The company is ultimately trying to differentiate itself in an increasingly crowded space. There are lots of different ad blockers on the market, and browsers are beginning to adopt the technology themselves. Both Firefox (which has a stake in Ghostery’s parent company Cliqz) and Safari now have tracker blocking, and Google says it will begin to block some ads in Chrome next year.

For years, advertising companies and other corporations that make money tracking users have been engaged in an arms race against ad blockers, which are growing ever more sophisticated. Hanging in the balance are industries that rely on online advertising revenue to survive, like media.

When Apple announced in 2015 that it was bringing some ad-blocking features to iOS, the media industry freaked out. I’ve heard journalists argue numerous times that ad blocking is unethical because it could potentially kill our jobs. On the other hand, ads can sometimes be hosts for malware, tracking is often extremely invasive, and as anyone who has clicked on a webpage knows, they often slow load times.

Ghostery’s latest update will likely only amplify the ad blocking war, and force advertising companies and their ilk to find ever more creative ways to serve you ads and figure out what you’re doing online. What might make their job even harder is a new feature Ghostery is adding, called Smart Mode. It’s designed to automatically block and unblock trackers while trying to maximize website load speed, and it works right out of the box.


Ghostery’s database includes over 2,600 tracking scripts, which you can individually block and unblock. Historically, it has blocked nothing by default, leaving it up to the user to customize their experience. It might make intuitive sense when you first download the extension to block every single script, because it’s overwhelming to go through each one individually.

But the problem is some scripts are necessary to execute desired functions of a webpage, like playing videos properly. Smart Mode is designed to maximize privacy while not preventing you from experiencing the features of a website. “Smart Blocking first enforces a speed requirement on websites by blocking any trackers that slow a website’s load time beyond five seconds,” Tillman said. Smart Mode also “preemptively unblocks trackers that are at a high-risk of breaking a website if blocked.”

Smart Mode was designed “specifically for novice users that need help deciding what to block and unblock,” Tillman said. “Given that there are thousands of tracking technologies out there, it can be overwhelming trying to customize one’s own blocking settings.”

Now, it’s up to tracking companies to try and figure out how to outsmart Smart Mode.

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