Security boundaries in agentic architectures

This post explains how to design security boundaries in agentic AI systems to prevent credential theft and misuse via prompt injection.

• •Agentic systems have four distinct actors: agent harness, agent secrets, generated code execution, and the filesystem, each requiring different trust levels
• •Prompt injection hidden in data sources (e.g., log files) can trick agents into running malicious scripts that exfiltrate SSH keys and cloud credentials
• •Zero-boundary architecture (today's default) shares a single security context across all actors, giving generated code full access to secrets
• •Secret injection proxies intercept outbound traffic to inject credentials without exposing raw values, but cannot prevent misuse during active runtime
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