ProCircular Information Security Experts Corner

Adblockers: Should you use them?

Posted by Kevin Wolfe on Nov 7, 2019 10:15:00 AM

Chances are that if you've used the internet in the last 15 years you've been subjected to more ads than there are grains of sand on a beach. There's also a good chance you've gotten sick of them and installed an Adblocker.

Adblockers block advertisements based on filter lists - sets of rules that match ads or other elements on webpages and prevent them from loading. This is how your adblocker can tell the difference between ads and content that you actually want to see. As advertisers frequently make small changes to their content in order to slip past these rules, filter lists are updated to match these changes. In this way, adblockers and advertisers are locked in a perpetual arms race.

I've always been a big advocate for adblockers, but I have friends who disagree. "It's how websites make their money," they say. "Ads are better than having to pay to view websites because everybody wins!"

Nope, you lose two things: privacy and security.

Ads may seem benign (though annoying) on the surface, but they have a dark underbelly. Advertisements are the primary way that you're tracked on the internet---when an ad loads on a page you visit, the advertiser sees that you've loaded it, what site you've loaded it on, and uses methods such as browser cookies or JavaScript fingerprinting to identify you and keep a record of every site you visit. This surveillance happens invisibly in the background, and there's no way to opt-out other than by blocking the advertisements entirely. By allowing ads you're allowing any and all advertisement companies to keep a record of all your online activity---with no oversight or accountability for how that information is used or who they sell it to.

In addition to the privacy concerns, there's a security risk in allowing advertisements as well. Malvertising is the use of legitimate advertising networks to disseminate ads loaded with malware. By allowing ads, even on sites you think you can trust, you're adding unnecessary risk by making yourself susceptible to attacks.

There are different categories of malvertising, but the most common three are:

  1. Drive-by downloads: when attackers can abuse features of the user's browser or operating system to download malicious files
  2. Deceptive downloads: where the attacker's ad masquerades as either a legitimate download link on the web page or as a different, but also seemingly-legitimate website (such as an Adobe Flash update - please don't ever use adobe flash).
  3. Scareware: which redirects where code embedded in the ad forces a redirect to a page that claims that your computer has been "compromised" and that you should call the "totally real phone number for Microsoft/the FBI/the IRS" that they display below in order to prevent "dire consequences". These warnings are never true but will often use techniques to make it difficult to navigate away from the webpage, preying on the non-tech-savvy and the elderly.

 

adblockers

 

Hopefully I've sold you on ad-blocking, but which one should you use?

Not all adblockers are created equal. Some have worse filter lists and can miss ads, some are more resource intensive and increase the load your browser, some replace a website's ads with their own or take money from ad networks to whitelist them (https://www.nytimes.com/2016/09/19/business/media/adblock-plus-created-to-protect-users-from-ads-opens-the-door.html), and some truly bad actors can introduce more privacy and security issues than they solve. Fortunately, I can make a recommendation that's widely regarded as the best out there, and is efficient, has great filter lists that update constantly, and is completely free and open-source.

**uBlock Origin** (not to be confused with just "uBlock")

uBlock Origin is an free and open-source browser extension available for Firefox , Chrome, and Microsoft Edge. It's designed to be easy to use, efficient, and updates automatically. Because it's open source, the code (available on GitHub) can and has been reviewed by security and tech professionals around the world, making it the safest and most effective adblocker out there.

Have more questions on why you should use an adblocker? Feel free to comment below or hit the contact ProCircular button today!

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