Adversarial Vulnerability Testing for Non-Differentiable ML Models

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Solution Overview

Problem

Existing adversarial robustness testing approaches are incompatible with non-differentiable machine learning models like tree ensembles, leading to a gap between research and practical applications, as they fail to efficiently assess vulnerabilities to adversarial examples in these widely used models.

Innovation Solution

A scalable whitebox attack method that smooths tree ensembles using temperature-controlled sigmoid functions, enabling gradient descent-based adversarial attacks, and leverages sampling and log-derivative approaches to efficiently detect vulnerabilities without causing computational pressure, incorporating noise injection and feature-dependent perturbation tolerance to improve search efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If gradient descent-based adversarial attacks are applied directly to tree ensemble models, then the attack efficiency is improved, but the method becomes incompatible with non-differentiable models like tree ensembles

Engineering Contradiction:
Improveattack efficiencyVSAvoidcompatibility with non-differentiable models
Core Design Contradiction:
ProductivityVSAdaptability or versatility

Solution Approach 1:

The patent introduces a differentiable surrogate model (neural network) as an intermediary to bridge the gap between gradient-based attack methods and non-differentiable tree ensemble models. The surrogate model is trained to mimic the behavior of the target tree ensemble, enabling efficient gradient-based adversarial attacks on the surrogate while transferring the generated adversarial examples to the original non-differentiable model for validation.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Adaptability or versatility

If tree ensembles are smoothed using temperature-controlled sigmoid functions, then gradient-based attacks become possible, but computational complexity increases

Engineering Contradiction:
Improveenablement of gradient-based attacksVSAvoidcomputational complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent applies temperature-controlled sigmoid functions to smooth the non-differentiable tree ensemble model, transforming it into a differentiable form that supports gradient-based attacks. By controlling the temperature parameter, the method balances between maintaining fidelity to the original model and enabling smooth gradients for optimization, thus resolving the computational complexity issue while maintaining attack effectiveness.

Inventive Principle:
Principle #35Parameter changes

3Reliability

If adversarial vulnerability testing is performed on tree ensemble models, then security assessment is improved, but the lack of analytical tools creates a gap between research and practical applications

Engineering Contradiction:
Improvesecurity assessment capabilityVSAvoidavailability of analytical tools
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The patent segments the adversarial attack process into distinct modules: (1) surrogate model training, (2) gradient-based adversarial example generation, and (3) validation on the original tree ensemble model. This modular segmentation creates reusable analytical tools that can be independently applied to different tree ensemble models, bridging the gap between research methodologies and practical security assessment tools.

Inventive Principle:
Principle #1Segmentation

Data Source

PatentUS12164649B2System and method for adversarial vulnerability testing of machine learning models
Publication Date: 2024.12.10 ROYAL BANK OF CANADA
  • US12164649B2 patent drawing
  • US12164649B2 patent drawing
  • US12164649B2 patent drawing

AI summary

A system and method for adversarial vulnerability testing of machine learning models is proposed that receives as an input, a representation of a non-differentiable machine learning model, transforms the input model into a smoothed model and conducts an adversarial search against the smoothed model to generate an output data value representative of a potential vulnerability to adversarial examples. Variant embodiments are also proposed, directed to noise injection, hyperparameter control, and exhaustive/sampling-based searches in an effort to balance computational efficiency and accuracy in practical implementation. Flagged vulnerabilities can be used to have models re-validated, re-trained, or removed from use due to an increased cybersecurity risk profile.