call_rpc · Frida MCP: Risk & Policy

WHAT IT DOES

What call_rpc does on Frida

AI agents invoke call_rpc to trigger actions in Frida. What it does depends on the arguments the agent supplies, and its effects often reach beyond the immediate call — builds kicked off, notifications sent, workflows started.

WHY IT NEEDS A POLICY

Why call_rpc needs a policy

This tool executes arbitrary functions exported by Frida scripts running inside attached processes. Since Frida enables dynamic instrumentation (hooking, memory access, code injection), calling RPC methods can trigger arbitrary code execution within the target process. The blast radius is high as it can manipulate process memory, bypass security controls, or execute arbitrary logic in any attached process.

From the tool's definition 'Call a function exported by a persistent script loaded via' — invokes RPC methods in dynamically instrumented processes via Frida

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

call_rpc Rate-limited

call_rpc stays usable, but rate-capped — a runaway agent can't fire it dozens of times a minute. Everything else on the server is denied unless you say otherwise.

View as policy code

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "call_rpc": {
      "limits": [
        {
          "counter": "call_rpc_rate",
          "window": "minute",
          "max": 10,
          "scope": "grant"
        }
      ]
    }
  }
}

RATE-LIMIT THIS TOOL →

Instant setup, no code required.

PolicyLayer is an MCP gateway: every tool call is checked against your rule before it reaches Frida, so you can run agents against it safely.

FAQ

Questions about call_rpc

What does the call_rpc tool do? +

Call a function exported by a persistent script loaded via. It is categorised as a Execute tool in the Frida MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.

How do I enforce a policy on call_rpc? +

Register the Frida MCP server in PolicyLayer and add a rule for call_rpc: allow, deny, rate-limit, or require approval. Point your MCP client at the PolicyLayer proxy URL and the rule is enforced on every call, before it reaches Frida. Nothing to install.

What risk level is call_rpc? +

call_rpc is a Execute tool with high risk. Execute tools should be rate-limited and have argument validation enabled.

Can I rate-limit call_rpc? +

Yes. Add a rate_limit block to the call_rpc rule in your PolicyLayer policy. For example, setting max: 10 and window: 60 limits the tool to 10 calls per minute. Rate limits are tracked per agent session and reset automatically.

How do I block call_rpc completely? +

Set action: deny in the PolicyLayer policy for call_rpc. The AI agent will receive a policy violation error and cannot call the tool. You can also include a reason field to explain why the tool is blocked.

What MCP server provides call_rpc? +

call_rpc is provided by the Frida MCP server (snowluma/mcp-frida). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.