Detail

Publication date: 4 de December, 2025

Toward Resilient CyberEdge Intelligence: Variational Graph Models and Data-Agnostic Poisoning in Federated Learning

In CyberEdge networks, where federated learning (FL) orchestrates intelligence across privacy-preserving edge devices, emerging model poisoning (MP) poses a critical threat to system resilience. This talk focuses on a new type of the data-untethered attack, where an adversarial variational graph autoencoder (VGAE) constructs malicious local model updates from benign updates, bypassing access to private training data. By extracting and regenerating high-order graph structural correlations among benign client models, the new VGAE-MP attack produces stealthy and effective poisoning that evades conventional detection and leads to a progressive degradation of global model accuracy. To counter such graph-driven, semantically aligned threats, we further present a visual explanation-based defense framework that transforms local updates into visual heat-map representations via Gradient-weighted Class Activation Mapping (GradCAM) and can enhance their separability through autoencoder-based feature projection. This approach exposes hidden discrepancies between benign and malicious updates that Euclidean distance/Cosine similarity-based defenses fail to capture. In addition, we discuss the escalating vulnerability of CyberEdge FL to advanced graph-based attacks as well as promising pathways toward more resilient and trustworthy distributed intelligence.

Presenter

Kai Li (CISTER - ISEP),

Date 10/12/2025 2:00 pm
Location DI Seminars Room and Google Meet
Host Bio Dr. Kai Li received the B.E. degree from Shandong University, China, in 2009, the M.S. degree from The Hong Kong University of Science and Technology, Hong Kong, in 2010, and the Ph.D. degree in computer science from the University of New South Wales, Sydney, Australia, in 2014. Funded by the CMU-Portugal Visiting Faculty and Researchers Program, currently, Dr. Li is a Visiting Scholar in the Department of Electrical and Computer Engineering, College of Engineering, Carnegie Mellon University (CMU), Pittsburgh, Pennsylvania, United States. From 2024 to 2025, he was a Visiting Scholar with the School of Electrical Engineering and Computer Science, TU Berlin, Germany. From 2016 to 2025, he served as a Senior Research Scientist at the CISTER Research Centre, Porto, Portugal, and concurrently as a CMU-Portugal Research Fellow, jointly supported by CMU and the Foundation for Science and Technology (FCT), Lisbon, Portugal. From 2023 to 2024, he was a Visiting Research Scientist with the Division of Electrical Engineering, Department of Engineering, University of Cambridge, UK. In 2022, he was a Visiting Scholar with the CyLab Security and Privacy Institute at CMU. Prior to these, he worked as a Post-Doctoral Research Fellow with the SUTD-MIT International Design Centre, Singapore University of Technology and Design (SUTD), Singapore, from 2014 to 2016. He also held positions as a Visiting Research Assistant with the ICT Centre, CSIRO, Brisbane, Australia, from 2012 to 2013, and as a Research Assistant with the Mobile Technologies Centre, The Chinese University of Hong Kong, from 2010 to 2011.