spawn_shell · Cobalt Strike MCP Server MCP: Risk & Policy

WHAT IT DOES

What spawn_shell does on Cobalt Strike MCP Server

AI agents invoke spawn_shell to trigger actions in Cobalt Strike 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 spawn_shell needs a policy

This tool allows execution of arbitrary shell commands on remote systems (beacons) without apparent constraints. In a red-team context, it can run commands with full privileges of the beacon process, potentially enabling lateral movement, data exfiltration, malware deployment, persistence mechanisms, or system compromise. Misuse by an AI agent could cause extensive damage across compromised infrastructure.

From the tool's definition Tool executes arbitrary shell commands on remote beacons. Description explicitly states 'Execute a shell command' with no restrictions on command types or parameters, enabling unrestricted code execution on compromised systems.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

spawn_shell Rate-limited

spawn_shell 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": {
    "spawn_shell": {
      "limits": [
        {
          "counter": "spawn_shell_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 Cobalt Strike MCP Server, so you can run agents against it safely.

FAQ

Questions about spawn_shell

What does the spawn_shell tool do? +

Execute a shell command on a beacon. It is categorised as a Execute tool in the Cobalt Strike 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 spawn_shell? +

Register the Cobalt Strike MCP Server MCP server in PolicyLayer and add a rule for spawn_shell: 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 Cobalt Strike MCP Server. Nothing to install.

What risk level is spawn_shell? +

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

Can I rate-limit spawn_shell? +

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

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

spawn_shell is provided by the Cobalt Strike MCP Server MCP server (mickeydb/cobalt-strike-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.