rubeus_harvest · Rubeus MCP Server MCP: Risk & Policy

WHAT IT DOES

What rubeus_harvest does on Rubeus MCP Server

AI agents invoke rubeus_harvest to trigger actions in Rubeus MCP Server. 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 rubeus_harvest needs a policy

This tool performs continuous credential harvesting by extracting Kerberos Ticket Granting Tickets (TGTs) from other users as they authenticate. It is part of a Kerberos abuse toolkit (Rubeus/Impacket) and enables persistent unauthorized access by stealing and auto-renewing authentication tokens.

From the tool's definition 'Continuously monitor for and harvest new TGTs', 'runs in a loop, extracting new TGTs as they appear', 'auto-renewing them to maintain access', 'capturing tickets from other users logging in'

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

rubeus_harvest Rate-limited

rubeus_harvest 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": {
    "rubeus_harvest": {
      "limits": [
        {
          "counter": "rubeus_harvest_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 Rubeus MCP Server, so you can run agents against it safely.

FAQ

Questions about rubeus_harvest

What does the rubeus_harvest tool do? +

Continuously monitor for and harvest new TGTs. Runs in a loop, extracting new TGTs as they appear and optionally auto-renewing them to maintain access. Useful for capturing tickets from other users logging in. It is categorised as a Execute tool in the Rubeus MCP Server MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.

How do I enforce a policy on rubeus_harvest? +

Register the Rubeus MCP Server MCP server in PolicyLayer and add a rule for rubeus_harvest: 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 Rubeus MCP Server. Nothing to install.

What risk level is rubeus_harvest? +

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

Can I rate-limit rubeus_harvest? +

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

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

rubeus_harvest is provided by the Rubeus MCP Server MCP server (schwarztim/sec-rubeus-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.