Key Takeaway
Defense-in-depth for LLM applications requires input validation, output filtering, privilege separation, and monitoring layers working together rather than relying on any single control. No single defense stops all LLM attacks. This guide covers the OWASP Top 10 for LLMs with practical detection and prevention implementations.
Prerequisites
- An LLM-powered application in production or nearing deployment
- Understanding of your application's LLM integration points (which features call the LLM, with what data)
- Familiarity with your LLM provider's safety features and content policies
- Application security fundamentals (input validation, output encoding, least privilege)
- Logging and monitoring infrastructure for security event detection
The LLM Attack Surface
LLM-powered applications introduce a fundamentally new attack surface: the model itself becomes a programmable component that can be influenced by untrusted input. Traditional application security assumes that code behavior is deterministic -- the same input always produces the same output. LLMs violate this assumption: their behavior can be altered by the content of the input in ways that no amount of traditional input validation can fully prevent. This is not a bug but a fundamental property of how language models work.
The OWASP Top 10 for LLM Applications (2025) categorizes the most critical risks: prompt injection, insecure output handling, training data poisoning, model denial of service, supply chain vulnerabilities, sensitive information disclosure, insecure plugin design, excessive agency, overreliance, and model theft. This guide focuses on the threats that engineering teams can mitigate through architecture and code: prompt injection, output security, PII protection, and denial of service.
Prompt Injection Defense
Unlock the full Knowledge Base
This article continues for 12 more sections. Upgrade to Pro for full access to all 93 articles.
That's just $0.11 per article
- Full access to all blueprints, frameworks, and playbooks
- Interactive checklists with progress tracking
- Downloadable templates (.xlsx, .pptx, .docx)
- Quarterly Technology Radar updates