syscall_direct_invoke

SERVERJshookmcp SOURCE@jshookmcp/jshook

High RISK CLASS

Category Execute

Parameters 00 required

Recommended Rate-limitedsee the rule below

Registry record Grade F, identity unverified Pull the record →

This record as markdown: /tools/io-github-vmoranv-jshookmcp/syscall-direct-invoke.md

WHAT IT DOES

What syscall_direct_invoke does on Jshookmcp

AI agents invoke syscall_direct_invoke to trigger actions in Jshookmcp. 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.

RISK

Why syscall_direct_invoke is rated High

Enables arbitrary low-level system calls, circumventing security controls and enabling malware-like operations.

From the tool's definition Direct NT syscall invocation, bypasses user-mode hooks, in-process execution

Attacks that exploit this kind of access

RECOMMENDED RULE

The rule that runs syscall_direct_invoke safely

PolicyLayer is an MCP gateway: it sits between your AI agents and Jshookmcp, and checks every tool call against a rule you set before the call runs. Nothing changes on the server itself. For syscall_direct_invoke, this is the rule to start with:

syscall_direct_invoke Rate-limited

syscall_direct_invoke 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": {
    "syscall_direct_invoke": {
      "limits": [
        {
          "counter": "syscall_direct_invoke_rate",
          "window": "minute",
          "max": 10,
          "scope": "grant"
        }
      ]
    }
  }
}

RATE-LIMIT THIS TOOL → Instant setup, no code required.

The button opens the PolicyLayer dashboard: create your workspace, connect Jshookmcp, apply this rule, and every syscall_direct_invoke call is checked against it from then on.

FAQ

Questions about syscall_direct_invoke

What does the syscall_direct_invoke tool do? +

Direct NT syscall invocation guidance. Resolves SSN for a given NT function and returns a stub template with usage instructions for in-process direct syscall invocation. Bypasses user-mode hooks on ntdll.dll. Win32 only. It is categorised as a Execute tool in the Jshookmcp MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.

How do I enforce a policy on syscall_direct_invoke? +

Register the Jshook MCP server in PolicyLayer and add a rule for syscall_direct_invoke: 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 Jshookmcp. Nothing to install.

What risk level is syscall_direct_invoke? +

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

Can I rate-limit syscall_direct_invoke? +

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

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

syscall_direct_invoke is provided by the Jshook MCP server (@jshookmcp/jshook). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

KEEP EXPLORING

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