A comprehensive study by NYU Tandon has discovered that ad blockers might inadvertently showcase more harmful advertisements to users. The findings raise significant questions about the effectiveness and transparency of these privacy tools.
Ad blockers, which are used by nearly 1 billion internet users to protect themselves from intrusive advertisements, might ironically expose users to even more problematic content. This startling revelation comes from a new study conducted by NYU Tandon School of Engineering, which will be presented at the 25th Privacy Enhancing Technologies Symposium on July 15, 2025.
The research scrutinized over 1,200 advertisements across the United States and Germany, revealing that users of Adblock Plus’s “Acceptable Ads” feature encountered 13.6% more problematic advertisements compared to those browsing without any ad-blocking software.
These findings challenge the commonly held belief that privacy tools universally enhance the online experience.
“While programs like Acceptable Ads aim to balance user and advertiser interests by permitting less disruptive ads, their standards often fall short of addressing user concerns comprehensively,” lead author Ritik Roongta, a doctoral student in the Computer Science and Engineering (CSE) Department at NYU Tandon, said in a news release.
The study utilized an AI-powered system to identify problematic ads at scale.
The researchers created a comprehensive taxonomy from advertising industry policies, regulatory guidelines and user feedback.
They defined seven categories of concerning content: inappropriate for minors, offensive or explicit material, deceptive health or financial claims, manipulative design tactics, intrusive user experiences, fraudulent schemes and undisclosed political content.
Their AI system, leveraging OpenAI’s GPT-4o-mini model, matched human expert judgments 79% of the time in identifying problematic content.
Significantly, the study uncovered that almost 10% of advertisements shown to minors violated regulations meant to protect them.
Ad selections under the “Acceptable Ads” program seemed particularly problematic, as existing approved exchanges increased the delivery of harmful content to privacy-conscious users, while newly added exchanges adhered more strictly to non-intrusive standards.
“This differential treatment of ad blocker users by ad exchanges raises serious questions,” Roongta added. “Do ad exchanges detect the presence of these privacy-preserving extensions and intentionally target their users with problematic content?”
The implications are far-reaching.
The study warns of a new potential risk: digital fingerprinting of privacy-aware users. This can create a “hidden cost” for those attempting to protect their online presence, making them identifiable targets.
The $740 billion digital advertising industry faces substantial revenue loss due to ad blockers, leading many websites to counteract with scripts that detect and mitigate ad-blocking software.
“The misleading nomenclature of terms like ‘acceptable’ or ‘better’ ads creates a perception of enhanced user experience, which is not fully realized,” added co-author Rachel Greenstadt, an NYU Tandon CSE professor and faculty member of the NYU Center for Cybersecurity, who oversaw the research.
The current study extends the earlier research by Greenstadt and Roongta, exposing another dimension of how privacy technologies may inadvertently harm users.
This compelling study raises important considerations about the real impact of ad blockers, steering a crucial conversation about privacy, user safety and the true efficacy of digital safeguards.
Source: NYU Tandon School of Engineering