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Proactive Hardening of LLM Defenses with HASTE

Authors: Henry Chen, Victor Aranda, Samarth Keshari, Ryan Heartfield, Nicole Nichols

Published: 2026-01-27

arXiv ID: 2601.19051v1

Added to Library: 2026-01-28 03:00 UTC

Red Teaming Safety

📄 Abstract

Prompt-based attack techniques are one of the primary challenges in securely deploying and protecting LLM-based AI systems. LLM inputs are an unbounded, unstructured space. Consequently, effectively defending against these attacks requires proactive hardening strategies capable of continuously generating adaptive attack vectors to optimize LLM defense at runtime. We present HASTE (Hard-negative Attack Sample Training Engine): a systematic framework that iteratively engineers highly evasive prompts, within a modular optimization process, to continuously enhance detection efficacy for prompt-based attack techniques. The framework is agnostic to synthetic data generation methods, and can be generalized to evaluate prompt-injection detection efficacy, with and without fuzzing, for any hard-negative or hard-positive iteration strategy. Experimental evaluation of HASTE shows that hard negative mining successfully evades baseline detectors, reducing malicious prompt detection for baseline detectors by approximately 64%. However, when integrated with detection model re-training, it optimizes the efficacy of prompt detection models with significantly fewer iteration loops compared to relative baseline strategies. The HASTE framework supports both proactive and reactive hardening of LLM defenses and guardrails. Proactively, developers can leverage HASTE to dynamically stress-test prompt injection detection systems; efficiently identifying weaknesses and strengthening defensive posture. Reactively, HASTE can mimic newly observed attack types and rapidly bridge detection coverage by teaching HASTE-optimized detection models to identify them.

🔍 Key Points

  • Introduction of HASTE (Hard-negative Attack Sample Training Engine), a modular framework for enhancing defenses against prompt-based attacks on LLMs through continuous adversarial prompt generation.
  • Demonstrated the effectiveness of hard-negative mining, achieving a 64% reduction in malicious prompt detection for baseline detectors, thereby showing significant improvements in model robustness.
  • Framework supports proactive (dynamic stress-testing) and reactive (mimicking new attacks) strategies for LLM defenses, contributing to adaptable security solutions in real-time environments.
  • Experimental results reveal that the HASTE framework optimizes model training cycles, significantly reducing the number of iterations needed for effective model convergence compared to baseline techniques.
  • Establishment of a comprehensive taxonomic structure for categorizing adversarial prompts, enhancing the capability to diagnose and improve detection strategies across varied attack types.

💡 Why This Paper Matters

The HASTE framework represents a significant advancement in the proactive hardening of LLM defenses against evolving prompt-based attacks. By combining dynamic adversarial prompt generation with systematic model refinement through hard-negative mining, this approach not only improves the detection efficacy of existing models but also supports the development of robust security measures tailored for real-world applications. Its modular framework allows for flexibility in adapting to new threats, ensuring it remains relevant as adversarial tactics evolve.

🎯 Why It's Interesting for AI Security Researchers

This paper is highly relevant for AI security researchers as it addresses a critical challenge in deploying large language models securely. The introduction of HASTE provides insights into how proactive defenses can be designed to adapt to emerging attack vectors, making it a valuable asset for those looking to strengthen AI systems against prompt-based exploits. The empirical evaluations presented highlight practical applications of the framework, making this work critical for ongoing research in LLM security.

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