Measuring the (Over)use of Service Workers for In-Page Push Advertising Purposes

TL;DR

This study analyzes the widespread deployment of Service Workers on the web, revealing their predominant use for in-page push advertising to bypass ad-blockers, with a significant recent increase in adoption.

Contribution

It provides the first large-scale analysis of Service Worker deployment and uncovers their primary use for in-page push advertising, highlighting a new ad delivery method.

Findings

Service Workers increased by 26% in 5 months

65.08% of SWs connect with third parties for advertising

SWs are mainly used for in-page push ads to bypass ad-blockers

Abstract

Rich offline experience, periodic background sync, push notification functionality, network requests control, improved performance via requests caching are only a few of the functionalities provided by the Service Worker (SW) API. This new technology, supported by all major browsers, can significantly improve users' experience by providing the publisher with the technical foundations that would normally require a native application. Albeit the capabilities of this new technique and its important role in the ecosystem of Progressive Web Apps (PWAs), it is still unclear what is their actual purpose on the web, and how publishers leverage the provided functionality in their web applications. In this study, we shed light in the real world deployment of SWs, by conducting the first large scale analysis of the prevalence of SWs in the wild. We see that SWs are becoming more and more popular, with the adoption increased by 26% only within the last 5 months. Surprisingly, besides their fruitful capabilities, we see that SWs are being mostly used for In-Page Push Advertising, in 65.08% of the SWs that connect with 3rd parties. We highlight that this is a relatively new way for advertisers to bypass ad-blockers and render ads on the user's displays natively.