CRAIJun 5, 2025

Sentinel: SOTA model to protect against prompt injections

arXiv:2506.05446v16 citationsh-index: 1Has Code
Originality Incremental advance
AI Analysis

This addresses the vulnerability of LLMs to malicious inputs for users relying on secure AI interactions, representing a strong specific gain rather than a foundational advancement.

The paper tackles the problem of prompt injection attacks on Large Language Models by introducing Sentinel, a detection model that achieves state-of-the-art performance with an average accuracy of 0.987 and an F1-score of 0.980 on an unseen test set.

Large Language Models (LLMs) are increasingly powerful but remain vulnerable to prompt injection attacks, where malicious inputs cause the model to deviate from its intended instructions. This paper introduces Sentinel, a novel detection model, qualifire/prompt-injection-sentinel, based on the \answerdotai/ModernBERT-large architecture. By leveraging ModernBERT's advanced features and fine-tuning on an extensive and diverse dataset comprising a few open-source and private collections, Sentinel achieves state-of-the-art performance. This dataset amalgamates varied attack types, from role-playing and instruction hijacking to attempts to generate biased content, alongside a broad spectrum of benign instructions, with private datasets specifically targeting nuanced error correction and real-world misclassifications. On a comprehensive, unseen internal test set, Sentinel demonstrates an average accuracy of 0.987 and an F1-score of 0.980. Furthermore, when evaluated on public benchmarks, it consistently outperforms strong baselines like protectai/deberta-v3-base-prompt-injection-v2. This work details Sentinel's architecture, its meticulous dataset curation, its training methodology, and a thorough evaluation, highlighting its superior detection capabilities.

Foundations

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