Explore the intricacies of small-subgroup attacks on large distributed systems in this 33-minute conference talk delivered by Omer Shlomovits at the Workshop on Attacks in Cryptography, held in conjunction with Crypto 2021. Delve into the MPC implementation stack and associated bugs, examining curves with co-factors and their real-world implications. Gain insights into Distributed Key Generation (DKG) and its vulnerabilities, with a focus on breaking Proof of Knowledge of EC-Dlog. Analyze the DKG Subgroup Attack summary and understand its practical applications through real-world attack scenarios.