Everyone has come across obnoxious and invasive internet advertisements at some point, but thankfully ad blocking software is pretty good at filtering them out. Not only do these blockers remove distracting ads and make web pages easier to read, but they also keep advertisers from tracking users, reduce bandwidth and battery usage, and even protect you from malware.
But not all ad blockers are created equal. Some do the opposite of what they are supposed to—inject ads instead of removing them.
What Is Ad Injection?
So, what is ad injection? Ad injection comes in different forms, but essentially it is a technique malicious actors use to insert ads into a user's browser.
In other words, ad injection allows third parties to monetize a user's web session to collect revenue, and so harm publishers, advertisers, and users alike.
Threat actors and scammers utilize ad injection not just to steal ad revenue, but also to direct unsuspecting victims to third party e-commerce sites or insert affiliate codes.
Is AllBlock an Ad Injector?
Imperva Research Labs recently discovered that an extension available on both Chrome and Opera browsers called AllBlock seems and acts just like an ad blocker, but is actually an ad injector.
According to Imperva, AllBlock works in a very simple way: it injects malicious JavaScript code into every new tab opened in a browser, then replaces legitimate links (usually on search engine result pages) with third party ones.
For example, if you had the AllBlock extension installed in your browser, typed "best budget smartphone" in a search engine, and clicked on, say, the third search result, you could be redirected to a different page than the one you decided to visit.
It's important to note that the extension actually does block advertisements, which obviously makes it seem legitimate to the average user and more difficult to detect. In fact, it was only after close inspection of AllBlock's source code that Imperva researchers suggested it was not just a regular ad blocker.
AllBlock was rated highly on the Chrome Web Store and Opera add-ons, where it was marketed as a powerful ad blocker designed to remove Facebook and YouTube ads. It has been removed from both since Imperva researchers published their findings.
Review Your Extensions
Chrome is by far the most popular internet browser, so presumably thousands of people added the AllBlock extension to their browser.
This highlights just how important it is to stay vigilant and periodically check if you have malicious or otherwise dangerous extensions installed—even good and useful extensions can degenerate over time, slow down the browser, and cause other problems.
To check which extensions you have installed in Chrome, click the menu icon (three dots) at the top right and navigate to More tools > Extensions.
To learn more about an extension, select Details. This should allow you to check for any red flags, like if an extension was added by a third party, or if it requires unusual permissions.
If you find a shady extension, just click Remove to get rid of it. And if there is an extension you don't use very often, you can simply Disable it and Enable when necessary.
Take Precautions
Apart from periodically reviewing your extensions, you should always take basic precautions online. It's always a good idea to download extensions from reputable companies, or at least do some research into the company behind the extension you want to install.
To add another layer of protection and improve your overall Chrome experience, consider installing extensions designed to improve your privacy and security.
With that said, Chrome is far from a perfect product (it uses too much memory, for example), so why not explore a few popular alternatives and see if they suit your needs better.