Sentinel: Open-Source Tool Automates Adversarial Security Testing for LLM Apps

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A developer has built Sentinel, an automated adversarial testing harness designed to identify security vulnerabilities in large language model (LLM) applications before they go live. The tool fires dynamic attack prompts across five OWASP Top 10 LLM vulnerability categories — including prompt injection, system prompt leakage, hallucination, excessive agency, and jailbreaking — and delivers a scored diagnostic report in under two minutes. Sentinel was created to fill a gap left by heavier enterprise tools like NVIDIA's Garak and Microsoft's PyRIT, which require complex configuration and are typically used by dedicated security teams. The tool includes a dashboard displaying pass rates, flagged categories, and collapsible attack-response inspection cards, and ships with an intentionally vulnerable demo chatbot to validate its detection capabilities. Sentinel was submitted as part of the MLH x DEV Writing Challenge and is publicly accessible via a live Vercel deployment.

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