Agent Guardrails and Controls | Block Engineering Blog

In our previous blog post, Securing the Model Context Protocol, we detailed the Model Context Protocol (MCP) system and discussed some security concerns and mitigations. As a brief recap, MCP provides agents with a means to accomplish tasks using defined tools; reducing the burden of using complex and varied APIs and integrations on the agent.

However, in our prior blog post we did not cover mitigations for injection attacks against LLMs that are performed by MCPs themselves. At the time, this was because we didn’t have any security advice we believed was helpful to offer.

However, that is the focus of this post where we outline a way of modelling this attack using the established threat model of browser security, and specifically CSRF (Cross-Site Request Forgery), to provide insights into novel mitigations we believe could help dramatically reduce the attack’s likelihood.

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