LLM Security Basics: The Full Threat Model

Large language models face a fundamental security flaw: they cannot separate instructions from data, making them vulnerable to "prompt injection" attacks. A 2025 Microsoft Copilot breach called EchoLeak showed how a single email could silently steal company files. The biggest risk occurs when an AI agent combines access to private data, external content, and outbound channels simultaneously. No single defense works reliably, so layered protections are essential.