unhook_syscall · MCPEmulate MCP: Risk & Policy

WHAT IT DOES

What unhook_syscall does on MCPEmulate

AI agents use unhook_syscall to create or update resources in MCPEmulate — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your MCPEmulate environment.

WHY IT NEEDS A POLICY

Why unhook_syscall needs a policy

Removing a syscall hook undoes a configuration change within an isolated emulation session. It modifies the emulator state (reversibly, since hooks can be re-added) but does not delete data irreversibly, execute external commands, or have financial impact. Write is the most appropriate category as it changes the configuration of an existing resource.

From the tool's definition 'Remove the syscall hook' — reverses a previously installed hook, modifying the emulator's syscall interception state

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

unhook_syscall Rate-limited

unhook_syscall stays usable, but capped — an agent stuck in a loop can't make hundreds of changes a minute. Everything else on the server is denied unless you say otherwise.

View as policy code

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "unhook_syscall": {
      "limits": [
        {
          "counter": "unhook_syscall_rate",
          "window": "minute",
          "max": 30,
          "scope": "grant"
        }
      ]
    }
  }
}

LIMIT THIS TOOL →

Instant setup, no code required.

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

FAQ

Questions about unhook_syscall

What does the unhook_syscall tool do? +

Remove the syscall hook. It is categorised as a Write tool in the MCPEmulate MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on unhook_syscall? +

Register the MCPEmulate MCP server in PolicyLayer and add a rule for unhook_syscall: 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 MCPEmulate. Nothing to install.

What risk level is unhook_syscall? +

unhook_syscall is a Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.

Can I rate-limit unhook_syscall? +

Yes. Add a rate_limit block to the unhook_syscall 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 unhook_syscall completely? +

Set action: deny in the PolicyLayer policy for unhook_syscall. 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 unhook_syscall? +

unhook_syscall is provided by the MCPEmulate MCP server (labguy94/mcpemulate). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.