When Language Becomes the Attack Vector: The Lethal Trifecta of AI Agents

This report analyzes the “Lethal Trifecta” in AI agent security—combining access to private data, untrusted inputs, and external communication—which enables zero‑click, indirect prompt‑injection data exfiltration through legitimate tools. It illustrates the risk with a calendar‑invite scenario and recommends four hard boundary layers—identity and scoped permissions, runtime data‑flow enforcement, agent/session isolation, and human‑in‑the‑loop approvals—aligning these controls with the OWASP Top 10 for LLM and agentic applications.