Layer-Wise Perturbations via Sparse Autoencoders for Adversarial Text Generation

With the rapid proliferation of Natural Language Processing (NLP), especially Large Language Models (LLMs), generating adversarial examples to jailbreak LLMs remains a key challenge for understanding model vulnerabilities and improving robustness. In this context, we propose a new black-box attack method that leverages the interpretability of large models. We introduce the Sparse Feature Perturbation Framework (SFPF), a novel approach for adversarial text generation that utilizes sparse autoencoders to identify and manipulate critical features in text. After using the SAE model to reconstruct hidden layer representations, we perform feature clustering on the successfully attacked texts to identify features with higher activations. These highly activated features are then perturbed to generate new adversarial texts. This selective perturbation preserves the malicious intent while amplifying safety signals, thereby increasing their potential to evade existing defenses. Our method enables a new red-teaming strategy that balances adversarial effectiveness with safety alignment. Experimental results demonstrate that adversarial texts generated by SFPF can bypass state-of-the-art defense mechanisms, revealing persistent vulnerabilities in current NLP systems.However, the method's effectiveness varies across prompts and layers, and its generalizability to other architectures and larger models remains to be validated.

Key Contributions

• Proposes SFPF, which uses sparse autoencoders to identify high-activation features in LLM hidden layers from successfully attacked prompts via KMeans clustering
• Introduces a red-teaming strategy that perturbs SAE-derived feature representations to generate adversarial texts without requiring token-level gradient optimization
• Demonstrates empirically that SFPF-generated adversarial examples bypass state-of-the-art LLM defense mechanisms across multiple benchmarks

🛡️ Threat Analysis

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