Coordinated Electromagnetic Side-Channel Attacks for Voter--Ballot Linking: A Case Study of the Brazilian E-Polling System

Abstract

In this work, we show how two adversaries (Eve and Mallory) can coordinate an electromagnetic side-channel attack to recon- struct the vote displayed on an e-voting machine (EVM) and link it to a specific voter (Alice). Assuming that Eve has access to a place adjacent to the e-polling room (e.g., restroom, unsupervised room), she performs vote reconstruction by intercepting un- intended electromagnetic emanations associated with the video signal. Meanwhile, Mallory observes when Alice is voting and reports this information to Eve over the Internet. To validate the most critical stage of the attack, we conduct a software-defined radio experiment using the official Brazilian e-voting interface and demonstrate through-wall vote reconstruction. Although conventional monitors are employed rather than official EVMs, our findings provide insights into information forensics and support security recommendations for government authorities responsible for e-voting systems.