enable_regex · Firegex MCP: Risk & Policy

WHAT IT DOES

What enable_regex does on Firegex

AI agents use enable_regex to create or update resources in Firegex — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Firegex environment.

WHY IT NEEDS A POLICY

Why enable_regex needs a policy

The tool modifies firewall configuration by changing a regex rule's enabled state. This is a Write operation because it alters configuration reversibly (can be disabled again). Severity is medium because enabling a firewall rule could allow or block traffic based on regex patterns, potentially affecting network behavior, but the action is reversible and doesn't delete data or cause financial harm.

From the tool's definition Tool enables (activates) a previously-disabled regex rule, modifying its state from disabled to enabled. This is a reversible state change that affects firewall/proxy behavior.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

enable_regex Rate-limited

enable_regex stays usable, but capped — an agent stuck in a loop can't make hundreds of changes a minute. Everything else on the server is denied unless you say otherwise.

View as policy code

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "enable_regex": {
      "limits": [
        {
          "counter": "enable_regex_rate",
          "window": "minute",
          "max": 30,
          "scope": "grant"
        }
      ]
    }
  }
}

LIMIT THIS TOOL →

Instant setup, no code required.

PolicyLayer is an MCP gateway: every tool call is checked against your rule before it reaches Firegex, so you can run agents against it safely.

FAQ

Questions about enable_regex

What does the enable_regex tool do? +

Enable a previously-disabled regex without deleting it. It is categorised as a Write tool in the Firegex MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on enable_regex? +

Register the Firegex MCP server in PolicyLayer and add a rule for enable_regex: 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 Firegex. Nothing to install.

What risk level is enable_regex? +

enable_regex is a Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.

Can I rate-limit enable_regex? +

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

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

enable_regex is provided by the Firegex MCP server (umbra2728/firegex-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.