john_benchmark · John The Ripper MCP: Risk & Policy

WHAT IT DOES

What john_benchmark does on John The Ripper

AI agents invoke john_benchmark to trigger actions in John The Ripper. 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 john_benchmark needs a policy

This tool triggers execution of John the Ripper benchmark operations on a remote system. While benchmarking itself is not destructive, it executes arbitrary code/commands on the remote Kali system via SSH, which constitutes an Execute action.

From the tool's definition Tool performs benchmarks using John the Ripper on a remote Kali system via SSH. The description indicates it 'test[s] cracking speed for different hash types' which involves executing John the Ripper operations on an external system.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

john_benchmark Rate-limited

john_benchmark 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": {
    "john_benchmark": {
      "limits": [
        {
          "counter": "john_benchmark_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 John The Ripper, so you can run agents against it safely.

FAQ

Questions about john_benchmark

What does the john_benchmark tool do? +

Run benchmarks to test cracking speed for different hash types. It is categorised as a Execute tool in the John The Ripper MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.

How do I enforce a policy on john_benchmark? +

Register the John The Ripper MCP server in PolicyLayer and add a rule for john_benchmark: 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 John The Ripper. Nothing to install.

What risk level is john_benchmark? +

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

Can I rate-limit john_benchmark? +

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

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

john_benchmark is provided by the John The Ripper MCP server (schwarztim/sec-john-the-ripper-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.