Model Leeching: An Extraction Attack Targeting LLMs
Lewis Birch William Hackett Stefan Trawicki Neeraj Suri Peter Garraghan
Model Leeching is a novel extraction attack targeting Large Language Models
(LLMs), capable of distilling task-specific knowledge from a target LLM into a
reduced parameter model. We demonstrate the effectiveness of our attack by
extracting task capability from ChatGPT-3.5-Turbo, achieving 73% Exact Match
(EM) similarity, and SQuAD EM and F1 accuracy scores of 75% and 87%,
respectively for only $50 in API cost. We further demonstrate the feasibility
of adversarial attack transferability from an extracted model extracted via
Model Leeching to perform ML attack staging against a target LLM, resulting in
an 11% increase to attack success rate when applied to ChatGPT-3.5-Turbo.