Securing Agents

Securing Agents

Goal

Prevent AI Agents from being manipulated into performing harmful actions, leaking context, or executing malicious code. Secure the "Agentic Supply Chain."

When to Use

• When defining a new agent's tools or permissions.
• When designing the prompt/system instruction for an agent.
• When integrating an agent with external APIs or databases.

Instructions

1. Least Privilege (Agency Control)

Agents should only have the permissions strictly necessary for their specific task.

• Tools: If an agent reads files, don't give it write_file access unless required.
• Scope: Restrict file system access to specific directories (Sandboxing).
• Approval: Require human-in-the-loop (HITL) for high-impact actions (e.g., delete_database, deploy_production).

2. Prompt Injection Defense

Sanitize and segment inputs to prevent "Ignore previous instructions" attacks.

• Delimiters: Use XML tags (e.g., <user_input>...</user_input>) to clearly separate data from instructions.
• System Prompt Hardening: Explicitly instruct the agent to prioritize system instructions over user input.
• Output Validation: Check if the agent's output looks like it was hijacked (e.g., suddenly speaking a different language or dumping internal state).

3. Tool Input Validation (Zero Trust)

Never assume the agent generated safe arguments for a tool.

• Validation: Use Zod/Pydantic to strictly validate the structure and content of tool arguments.
• Sanitization: Prevent command injection (e.g., if a tool runs a shell command, escape all arguments).

4. Monitoring & Observability

• Log Everything: Inputs, outputs, tool calls, and reasoning steps.
• Anomaly Detection: Flag if an agent tries to access /.env or /etc/passwd.
• Circuit Breakers: If an agent fails or errors 3 times in a row, kill the process to prevent cascading failures.

Constraints

✅ Do

• Implement "Zero-Trust Tooling": Verify every API call the agent tries to make.
• Use distinct identity/credentials for each agent to limit blast radius.
• Sanitize all content entering the agent's context (Memory Poisoning prevention).
• Treat "System Prompts" as sensitive code (protect them from leakage).
• Follow OWASP Top 10 for LLM Applications & Agentic AI (2025/2026).

❌ Don't

• DO NOT give an agent direct, unrestricted exec or run_shell_command access without a sandbox.
• DO NOT let agents self-modify their own system prompts or code without strict review.
• DO NOT store secrets in the agent's context window / conversation history.

Output Format

• security_policy.json: Defining allowed tools and scopes for the agent.
• system_prompt_hardening_checklist.md.

Dependencies

• ../conducting-security-audit/SKILL.md