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Do Internal Layers of LLMs Reveal Patterns for Jailbreak Detection?

Authors: Sri Durga Sai Sowmya Kadali, Evangelos E. Papalexakis

Published: 2025-10-08

arXiv ID: 2510.06594v2

Added to Library: 2025-10-13 12:01 UTC

Red Teaming

๐Ÿ“„ Abstract

Jailbreaking large language models (LLMs) has emerged as a pressing concern with the increasing prevalence and accessibility of conversational LLMs. Adversarial users often exploit these models through carefully engineered prompts to elicit restricted or sensitive outputs, a strategy widely referred to as jailbreaking. While numerous defense mechanisms have been proposed, attackers continuously develop novel prompting techniques, and no existing model can be considered fully resistant. In this study, we investigate the jailbreak phenomenon by examining the internal representations of LLMs, with a focus on how hidden layers respond to jailbreak versus benign prompts. Specifically, we analyze the open-source LLM GPT-J and the state-space model Mamba2, presenting preliminary findings that highlight distinct layer-wise behaviors. Our results suggest promising directions for further research on leveraging internal model dynamics for robust jailbreak detection and defense.

๐Ÿ” Key Points

  • The paper presents a novel method of utilizing internal layer representations of large language models (LLMs) to detect jailbreak prompts, highlighting a new area of research within AI security.
  • It utilizes tensor decomposition techniques (CP decomposition) to analyze the dimensions of variation within the hidden layers of LLMs, providing a structured approach to distinguishing between benign and malicious prompts.
  • Results indicate that specific internal representations, particularly from the Multi-Head Attention outputs in GPT-J and Mixer outputs in Mamba-2, significantly outperform layer outputs in classifying prompts as jailbreak or benign.
  • The framework developed allows for effective binary classification using standard machine learning classifiers, showing promise for real-world applications in enhancing LLM security against adversarial exploits.
  • The findings suggest that different layers of a model exhibit unique response patterns to varied inputs, indicating potential pathways for future enhancements in model architecture for improved jailbreak detection.

๐Ÿ’ก Why This Paper Matters

This paper is significant in addressing a critical challenge facing the deployment of LLMs in real-world applications. By exploring the internal dynamics of these models, the authors not only provide a method for effective detection of jailbreaks but also open avenues for future research in understanding how deeper model representations can be leveraged for model safety and robust system design. The preliminary findings suggest the utility of low-cost, efficient detection methods that could easily be incorporated into existing systems.

๐ŸŽฏ Why It's Interesting for AI Security Researchers

This paper would be of keen interest to AI security researchers as it tackles a pressing vulnerability of large language modelsโ€”jailbreaking. The introduction of methods to analyze internal model behaviors offers a promising approach to fortifying LLM security. Researchers could build on this work to explore more sophisticated detection methods, improve defenses against evolving threats, and ultimately enhance the safety and reliability of conversational AI systems.

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