arXiv Computation and Language By Shuze Liu, Qianwen Guo, Yushun Dong

An Embarrassingly Simple Detector for Model Extraction Attacks in Large Language Model API Traffic

Read the original on arXiv Computation and Language →

The paper presents a simple detector for model extraction attacks on large language model APIs. It frames detection as a benign‑calibrated traffic‑window distribution test, embedding queries into a semantic space and using maximum mean discrepancy (MMD) to compare against historical benign traffic. Evaluated on fourteen attacker‑normal query pairs across four extraction scenarios, MMD achieves near‑perfect true‑positive rates while maintaining a 0.3% false‑positive rate, outperforming several existing baselines.

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