rubeus_renew · Rubeus MCP Server MCP: Risk & Policy

WHAT IT DOES

What rubeus_renew does on Rubeus MCP Server

AI agents invoke rubeus_renew 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_renew needs a policy

This tool executes Kerberos ticket renewal operations against an Active Directory environment. It interacts with external authentication infrastructure (KDC) and can auto-renew continuously, enabling persistent unauthorized access. It is an active operation with security implications (privilege persistence), placing it in Execute.

From the tool's definition 'Renew an existing TGT to extend its validity period' and 'maintaining persistent access without re-authentication' — this triggers external Kerberos operations via Rubeus/Impacket to manipulate authentication tickets

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

rubeus_renew Rate-limited

rubeus_renew 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_renew": {
      "limits": [
        {
          "counter": "rubeus_renew_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_renew

What does the rubeus_renew tool do? +

Renew an existing TGT to extend its validity period. Can optionally auto-renew continuously until the renewable lifetime expires. Useful for maintaining persistent access without re-authentication. 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_renew? +

Register the Rubeus MCP Server MCP server in PolicyLayer and add a rule for rubeus_renew: 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_renew? +

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

Can I rate-limit rubeus_renew? +

Yes. Add a rate_limit block to the rubeus_renew 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_renew completely? +

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

rubeus_renew 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.