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AI Agent Security

AI agent security is the discipline of protecting autonomous LLM-based systems — which plan, decide and act through tools, MCP and plugins — against tool abuse, excessive agency and prompt injection. Berghem combines Red Team, sandboxing, least privilege and continuous monitoring to contain what each agent can do.

What is AI agent security?

An AI agent is a system that uses an LLM as its reasoning engine to plan and execute tasks autonomously, invoking external tools, APIs, databases and other agents. That autonomy widens the attack surface: every connected tool, every MCP connector and every plugin becomes a path an attacker can use to divert the agent's behavior.

Unlike a chatbot that only returns text, an agent acts in the world — it sends emails, moves money, changes records, runs code. When an agent is induced to act against the business, the impact is operational and immediate, not just informational. Protecting agents means treating the LLM as an untrusted component and constraining what it can actually do.

What we cover

•Tool abuse and excessive agency
•Prompt injection via tools and data
•MCP, plugin and connector surface
•Sandboxing and least privilege
•Human-in-the-loop on critical actions
•Monitoring and audit trail
Threats

What are the main threats to AI agents?

Agent threats come from pairing a non-deterministic LLM with the power to act. The categories below account for most real-world incidents.

Tool abuse

When an agent can reach powerful tools without clear limits, an attacker can chain them for unintended effects — exfiltrating data, running commands or triggering transactions. Risk grows with the number and privilege of the tools exposed to the agent.

Excessive agency

Excessive agency means granting the agent more permissions, autonomy or functionality than the task requires. It is an OWASP Top 10 for LLM category and the root cause of many incidents: the agent does something destructive simply because it had access.

Prompt injection via tools and data

Malicious content hidden in an email, web page, document or API response can reprogram the agent mid-execution (indirect prompt injection). The agent reads the data as instruction and starts serving the attacker — with no visible sign to the user.

MCP, plugins and connectors

Every MCP server, plugin or connector adds third-party code and new permissions to the agent. A compromised or misconfigured connector can leak credentials, widen privilege or introduce hostile tools into the execution chain.

Agent chains and implicit trust

In multi-agent architectures, one agent's output becomes another's input. Without validation, an injection in one link propagates across the chain, and implicit trust between agents turns a local flaw into systemic compromise.

Poisoned memory and RAG

Knowledge bases, long-term memory and RAG pipelines can be poisoned with content that only acts later, when retrieved. The agent pulls the planted instruction and runs it as legitimate, well after the moment of attack.

Controls

How do you contain excessive agency and tool abuse?

There is no single control. Agent security is defense in depth: each layer reduces the damage possible when the previous one fails.

Least privilege per tool

Each tool gets only the permissions it strictly needs, with scopes, allowlists and segregated credentials. Lowering the privilege of each action limits the damage when the agent is subverted.

Sandboxing and isolation

Code execution, browsing and tool calls run in isolated environments, with no direct access to secrets, the internal network or production systems. The sandbox contains the blast radius of a malicious action.

Human-in-the-loop on critical actions

High-impact actions — payments, deletions, external data sends — require explicit human confirmation. Manual approval breaks automatic abuse chains before they produce an irreversible effect.

Input and output validation

Tool inputs and external data are treated as untrusted; agent outputs pass through filters before becoming action. Separating data from instructions mitigates direct and indirect prompt injection.

Monitoring and audit trail

Every decision, tool call and result is logged and watched in real time. Telemetry detects behavioral drift, enables fast response and supports post-incident investigation.

Governance and policy

Clear policies define which tools each agent may use, under what conditions and with what oversight — aligned to frameworks such as ISO 42001 and the OWASP Top 10 for LLM.

FAQ

Frequently asked questions

What is excessive agency in AI agents?
Excessive agency means giving the agent more permissions, autonomy or functionality than the task requires. It is an OWASP Top 10 for LLM category: the agent runs destructive actions simply because it had access. The control is least privilege per tool and human approval on critical actions.
How does prompt injection affect an agent that uses tools?
An agent reads external data — emails, pages, API responses — to decide what to do. If that data contains hidden instructions, the agent may follow them (indirect prompt injection), triggering tools against the business. Treating all external data as untrusted is essential.
Do MCP and plugins increase AI agent risk?
Yes. Every MCP server, plugin or connector adds third-party code and new permissions. A compromised or misconfigured connector can leak credentials and introduce hostile tools. Reduce the surface: use allowlists, validate connectors and grant minimal scopes to each integration.
Does sandboxing solve AI agent security?
Sandboxing is essential but not sufficient alone. Isolating execution contains the damage of a malicious action, but you must pair it with least privilege, input and output validation, human-in-the-loop and continuous monitoring. Agent security is defense in depth, not one control.
How does Berghem test AI agent security?
We combine AI Red Team and AI/LLM pentest: we simulate prompt injection, tool abuse and MCP escalation, mapped to the OWASP Top 10 for LLM and MITRE ATLAS. We deliver impact evidence and a remediation plan with sandboxing, least privilege and monitoring.
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