124 citations · 1.2k across the 61 of their papers we have counts for
69 papers
Welcome to the Dark Side: Analyzing the Revenue Flows of Fraud in the Online Ad Ecosystem
Emmanouil Papadogiannakis, Nicolas Kourtellis, Panagiotis Papadopoulos +1
The online advertising market has recently reached the 500 billion dollar mark. To accommodate the need to match a user with the highest bidder at a fraction of a second, it has mo…
A longitudinal study of the top 1% toxic Twitter profiles
Hina Qayyum, Benjamin Zi Hao Zhao, Ian D. Wood +3
Toxicity is endemic to online social networks including Twitter. It follows a Pareto like distribution where most of the toxicity is generated by a very small number of profiles an…
Poster: Sponge ML Model Attacks of Mobile Apps
Souvik Paul, Nicolas Kourtellis
Machine Learning (ML)-powered apps are used in pervasive devices such as phones, tablets, smartwatches and IoT devices. Recent advances in collaborative, distributed ML such as Fed…
A Survey on Privacy of Personal and Non-Personal Data in B5G/6G Networks
Chamara Sandeepa, Bartlomiej Siniarski, Nicolas Kourtellis +2
The upcoming Beyond 5G (B5G) and 6G networks are expected to provide enhanced capabilities such as ultra-high data rates, dense connectivity, and high scalability. It opens many po…
Privacy-Preserving Online Content Moderation: A Federated Learning Use Case
Pantelitsa Leonidou, Nicolas Kourtellis, Nikos Salamanos +1
Users are daily exposed to a large volume of harmful content on various social network platforms. One solution is developing online moderation tools using Machine Learning techniqu…
The Hitchhiker's Guide to Facebook Web Tracking with Invisible Pixels and Click IDs
Paschalis Bekos, Panagiotis Papadopoulos, Evangelos P. Markatos +1
Over the past years, advertisement companies have used various tracking methods to persistently track users across the web. Such tracking methods usually include first and third-pa…
Hierarchical Federated Learning with Privacy
Varun Chandrasekaran, Suman Banerjee, Diego Perino +1
Federated learning (FL), where data remains at the federated clients, and where only gradient updates are shared with a central aggregator, was assumed to be private. Recent work d…
FLaaS: Cross-App On-device Federated Learning in Mobile Environments
Kleomenis Katevas, Diego Perino, Nicolas Kourtellis
Federated Learning (FL) has recently emerged as a popular solution to distributedly train a model on user devices improving user privacy and system scalability. Major Internet comp…
YouTubers Not madeForKids: Detecting Channels Sharing Inappropriate Videos Targeting Children
Myrsini Gkolemi, Panagiotis Papadopoulos, Evangelos P. Markatos +1
In the last years, hundreds of new Youtube channels have been creating and sharing videos targeting children, with themes related to animation, superhero movies, comics, etc. Unfor…
A Survey on Privacy for B5G/6G: New Privacy Challenges, and Research Directions
Chamara Sandeepa, Bartlomiej Siniarski, Nicolas Kourtellis +2
Massive developments in mobile wireless telecommunication networks have been made during the last few decades. At present, mobile users are getting familiar with the latest 5G netw…
A deep dive into the consistently toxic 1% of Twitter
Hina Qayyum, Benjamin Zi Hao Zhao, Ian D. Wood +3
Misbehavior in online social networks (OSN) is an ever-growing phenomenon. The research to date tends to focus on the deployment of machine learning to identify and classify types…
Leveraging Google's Publisher-specific IDs to Detect Website Administration
Emmanouil Papadogiannakis, Panagiotis Papadopoulos, Evangelos P. Markatos +1
Digital advertising is the most popular way for content monetization on the Internet. Publishers spawn new websites, and older ones change hands with the sole purpose of monetizing…
Who Funds Misinformation? A Systematic Analysis of the Ad-related Profit Routines of Fake News sites
Emmanouil Papadogiannakis, Panagiotis Papadopoulos, Evangelos P. Markatos +1
Fake news is an age-old phenomenon, widely assumed to be associated with political propaganda published to sway public opinion. Yet, with the growth of social media, it has become…
Measuring the (Over)use of Service Workers for In-Page Push Advertising Purposes
George Pantelakis, Panagiotis Papadopoulos, Nicolas Kourtellis +1
Rich offline experience, periodic background sync, push notification functionality, network requests control, improved performance via requests caching are only a few of the functi…
PPFL: Privacy-preserving Federated Learning with Trusted Execution Environments
Fan Mo, Hamed Haddadi, Kleomenis Katevas +3
We propose and implement a Privacy-preserving Federated Learning () framework for mobile systems to limit privacy leakages in federated learning. Leveraging the widespread pr…
A First Look into the Structural Properties and Resilience of Blockchain Overlays
Aristodemos Paphitis, Nicolas Kourtellis, Michael Sirivianos
Blockchain (BC) systems are highly distributed peer-to-peer networks that offer an alternative to centralized services and promise robustness to coordinated attacks. However, the r…
YouTubing at Home: Media Sharing Behavior Change as Proxy for MobilityAround COVID-19 Lockdowns
Yelena Mejova, Nicolas Kourtellis
Compliance with public health measures, such as restrictions on movement and socialization, is paramount in limiting the spread of diseases such as the severe acute respiratory syn…
The Rise and Fall of Fake News sites: A Traffic Analysis
Manolis Chalkiadakis, Alexandros Kornilakis, Panagiotis Papadopoulos +2
Over the past decade, we have witnessed the rise of misinformation on the Internet, with online users constantly falling victims of fake news. A multitude of past studies have anal…
Under the Spotlight: Web Tracking in Indian Partisan News Websites
Vibhor Agarwal, Yash Vekaria, Pushkal Agarwal +5
India is experiencing intense political partisanship and sectarian divisions. The paper performs, to the best of our knowledge, the first comprehensive analysis on the Indian onlin…
Differential Tracking Across Topical Webpages of Indian News Media
Yash Vekaria, Vibhor Agarwal, Pushkal Agarwal +4
Online user privacy and tracking have been extensively studied in recent years, especially due to privacy and personal data-related legislations in the EU and the USA, such as the…
User Tracking in the Post-cookie Era: How Websites Bypass GDPR Consent to Track Users
Emmanouil Papadogiannakis, Panagiotis Papadopoulos, Nicolas Kourtellis +1
During the past few years, mostly as a result of the GDPR and the CCPA, websites have started to present users with cookie consent banners. These banners are web forms where the us…
FLaaS: Federated Learning as a Service
Nicolas Kourtellis, Kleomenis Katevas, Diego Perino
Federated Learning (FL) is emerging as a promising technology to build machine learning models in a decentralized, privacy-preserving fashion. Indeed, FL enables local training on…
Not one but many Tradeoffs: Privacy Vs. Utility in Differentially Private Machine Learning
Benjamin Zi Hao Zhao, Mohamed Ali Kaafar, Nicolas Kourtellis
Data holders are increasingly seeking to protect their user's privacy, whilst still maximizing their ability to produce machine models with high quality predictions. In this work,…
S2CE: A Hybrid Cloud and Edge Orchestrator for Mining Exascale Distributed Streams
Nicolas Kourtellis, Herodotos Herodotou, Maciej Grzenda +2
The explosive increase in volume, velocity, variety, and veracity of data generated by distributed and heterogeneous nodes such as IoT and other devices, continuously challenge the…