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Model Extraction

Model extraction is an attack where adversaries use repeated queries to recreate a deployed machine learning model. By analyzing outputs in response to crafted inputs, attackers can approximate the model’s parameters, decision boundaries, or architecture—effectively stealing the intellectual property encoded in the model.

This attack is also referred to as model cloning or reverse engineering. It is especially prevalent in public-facing APIs or subscription-based ML products, where attackers can gain black-box access and observe outputs at scale.

Motivations include:

  • IP theft: Rebuilding a valuable model without access to the original training pipeline.
  • Adversarial planning: Understanding the model’s weaknesses for later exploitation.
  • Reidentification: Using model structure to infer sensitive attributes or training data.

Model extraction is feasible even with limited access if the attacker uses:

  • Diverse or random input queries.
  • Adaptive sampling strategies.
  • Membership inference to identify training samples.

Defense strategies include:

  • Output obfuscation (e.g., reducing precision).
  • Query rate limiting and behavioral fingerprinting.
  • Watermarking or canary data insertion.
  • Model distillation with defensive tuning.

Resources:

OWASP ML05:2023 Model Theft

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