Perceptual Ad Blocking Study paints grim picture

Martin Brinkmann
Nov 12, 2018
Updated • Nov 12, 2018

Advertisement blockers address a growing number of issues related to online advertisement: from online tracking to sell higher paying ads over saving bandwidth and improving page load time, to blocking malware that is distributed through advertising channels.

One downside to ad blocking is that some publishers cannot sustain their business any longer; means, they either go out of business or use other means of earning revenue which may be even more problematic than ads. Some publishers implement anti ad blocking mechanics on their sites to block ad blockers from working correctly or running at all.

Princeton researchers created a software last year that used a different approach to detect and block advertisement. Instead of relying on hostnames or code snippets, the solution of the Princeton researchers mimiced how Internet users identify advertisement on websites.

A perceptual ad blocker is not that interested in code that ads use. It uses visual cues to identify advertisement instead; this includes subtle cues that sites are often required to show to users when page elements are sponsored -- e.g. sponsored or advertisement labels -- but also close buttons or icons on ads by ad companies such as Google.

The proof-of-concept extension for Google Chrome highlighted advertisement on Facebook and on the web but did not block it.

Advertisers and publishers can make changes to how advertisement is delivered to bypass conventional ad blocking extensions that rely on hostnames or code snippets to block ads.

While that is a short-lived benefit, as blocking lists get updated frequently with new data, it is one part of an arms race between publishers and advertising companies on the one side, and ad blocking programs and users on the other.

perceptual ad blocking
Triggering perceptual ad blockers with non-ad content.

The visual nature of perceptual ad blockers should, in theory, make it difficult for advertisers and publishers to modify advertisement to avoid detection and thus blocking.

The Princeton researchers hoped that perceptual ad blocking would end the arms race as advertisers would have to change the visual nature of the advertisement to avoid detection. Requirements, legal or self-regulatory, limit certain forms of change so that it would become difficult and sometimes impossible to change certain elements of an online ad.

Perceptual ad blockers have weaknesses

Researchers at Stanford University and CISPA Helmholtz Center for Information Security published the research paper Ad-versarial: Defeating Perceptual Ad-Blocking recently in which they refute the claim that perceptual ad blocking could put an end to the arms race between publishers and Internet users.

We show that perceptual ad-blocking engenders a new arms race that likely disfavors ad-blockers. Unexpectedly, perceptual ad-blocking can also introduce new vulnerabilities that let an attacker bypass web security boundaries and mount DDoS attacks.

The researchers devised eight different strategies to attack perceptual ad blockers and grouped these into four categories:

  • Attacks against Data Collection and Training -- if the perceptual ad blocking systems use crowd sourcing, most do according to the searchers, then it may be possible to dilute the learning process and thus the effectiveness of the blocking by submitting training data with visual backdoors or through other means.
  • Attacks against Page Segmentation -- the attacks targets blockers that "segment webpages based on their DOM" either by overloading through the use of a large number of HTML elements or by using techniques such as image sprites and CSS styles.
  • Attacks against Classification -- classification determines whether an element is considered an advertisement or not. Attacks that target classification aim to evade detection or detect the use of ad blockers. The researchers discovered, for example, that "most visual classifiers, the perturbation
    necessary to induce mis-classification [was] near-imperceptible to humans".
  • Attacks against Ad-Blocker Actions -- sites may exploit the high-privilege context in which ad blockers run, e.g. to block non-ad parts of a site for all users that use an advertisement blocker or by triggering requests.

The researchers evaluated the effectiveness of attacks and concluded that "all visual ad-detection techniques are fundamentally broken in the challenging attack model" that they used.

You can check out the research project's Github page here.

Perceptual Ad Blocking Study paints grim picture
Article Name
Perceptual Ad Blocking Study paints grim picture
Researchers at Stanford University and CISPA Helmholtz Center for Information Security published the research paper Ad-versarial: Defeating Perceptual Ad-Blocking recently.
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  1. ilev said on August 4, 2012 at 7:53 pm

    Doesn’t Windows 8 know that www. or http:// are passe ?

    1. Martin Brinkmann said on August 4, 2012 at 7:57 pm

      Well it is a bit difficulty to distinguish between domains and files for instance.

    2. Leonidas Burton said on September 4, 2023 at 4:51 am

      I know a service made by google that is similar to Google bookmarks.

  2. VioletMoon said on August 16, 2023 at 5:26 pm

    @Ashwin–Thankful you delighted my comment; who knows how many “gamers” would have disagreed!

  3. Karl said on August 17, 2023 at 10:36 pm


    The comments section under this very article (3 comments) is identical to the comments section found under the following article:

    Not sure what the issue is, but have seen this issue under some other articles recently but did not report it back then.

  4. Anonymous said on August 25, 2023 at 11:44 am

    Omg a badge!!!
    Some tangible reward lmao.

    It sucks that redditors are going to love the fuck out of it too.

  5. Scroogled said on August 25, 2023 at 10:57 pm

    With the cloud, there is no such thing as unlimited storage or privacy. Stop relying on these tech scums. Purchase your own hardware and develop your own solutions.

    1. lollmaoeven said on August 27, 2023 at 6:24 am

      This is a certified reddit cringe moment. Hilarious how the article’s author tries to dress it up like it’s anything more than a png for doing the reddit corporation’s moderation work for free (or for bribes from companies and political groups)

  6. El Duderino said on August 25, 2023 at 11:14 pm

    Almost al unlmited services have a real limit.

    And this comment is written on the dropbox article from August 25, 2023.

  7. John G. said on August 26, 2023 at 1:29 am

    First comment > @ilev said on August 4, 2012 at 7:53 pm

    For the God’s sake, fix the comments soon please! :[

  8. Kalmly said on August 26, 2023 at 4:42 pm

    Yes. Please. Fix the comments.

  9. Kim Schmidt said on September 3, 2023 at 3:42 pm

    With Google Chrome, it’s only been 1,500 for some time now.

    Anyone who wants to force me in such a way into buying something that I can get elsewhere for free will certainly never see a single dime from my side. I don’t even know how stupid their marketing department is to impose these limits on users instead of offering a valuable product to the paying faction. But they don’t. Even if you pay, you get something that is also available for free elsewhere.

    The algorithm has also become less and less savvy in terms of e.g. English/German translations. It used to be that the bot could sort of sense what you were trying to say and put it into different colloquialisms, which was even fun because it was like, “I know what you’re trying to say here, how about…” Now it’s in parts too stupid to translate the simplest sentences correctly, and the suggestions it makes are at times as moronic as those made by Google Translations.

    If this is a deep-learning AI that learns from users’ translations and the phrases they choose most often – which, by the way, is a valuable, moneys worthwhile contribution of every free user to this project: They invest their time and texts, thereby providing the necessary data for the AI to do the thing as nicely as they brag about it in the first place – alas, the more unprofessional users discovered the translator, the worse the language of this deep-learning bot has become, the greater the aggregate of linguistically illiterate users has become, and the worse the language of this deep-learning bot has become, as it now learns the drivel of every Tom, Dick and Harry out there, which is why I now get their Mickey Mouse language as suggestions: the inane language of people who can barely spell the alphabet, it seems.

    And as a thank you for our time and effort in helping them and their AI learn, they’ve lowered the limit from what was once 5,000 to now 1,500…? A big “fuck off” from here for that! Not a brass farthing from me for this attitude and behaviour, not in a hundred years.

  10. Anonymous said on September 28, 2023 at 8:19 am

    When will you put an end to the mess in the comments?

  11. RIP said on September 28, 2023 at 9:36 am

    Ghacks comments have been broken for too long. What article did you see this comment on? Reply below. If we get to 20 different articles we should all stop using the site in protest.

    I posted this on [] so please reply if you see it on a different article.

    1. RIP said on September 28, 2023 at 11:01 am

      Comment redirected me to [] which seems to be the ‘real’ article it is attached to

  12. RIP said on September 28, 2023 at 10:48 am

    Comment redirected me to [] which seems to be the ‘real’ article it is attached to

  13. Mystique said on September 28, 2023 at 12:13 pm

    Article Title: Reddit enforces user activity tracking on site to push advertising revenue
    Article URL:

    No surprises here. This is just the beginning really. I cannot see a valid reason as to why anyone would continue to use the platform anymore when there are enough alternatives fill that void.

  14. justputthispostanywhere said on September 29, 2023 at 3:59 am

    I’m not sure if there is a point in commenting given that comments seem to appear under random posts now, but I’ll try… this comment is for

    My temporary “solution”, if you can call it that, is to use a VPN (Mullvad in my case) to sign up for and access Reddit via a European connection. I’m doing that with pretty much everything now, at least until the rest of the world catches up with GDPR. I don’t think GDPR is a magical privacy solution but it’s at least a first step.

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