Enumerate subdomains using DNS brute force (active reconnaissance)
AI agents invoke subdomain_enum_active to trigger actions in MCP Recon. 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.
This tool performs active DNS brute-force enumeration, meaning it sends network requests to external targets to discover subdomains. This constitutes active probing/scanning of external infrastructure, which falls under Execute rather than Read — it generates outbound traffic with side effects on target systems (log entries, potential detection) rather than purely querying local or passive data sources.
From the tool's definition Enumerate subdomains using DNS brute force (active reconnaissance)
Documented attack patterns abuse exactly the kind of access subdomain_enum_active gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and MCP Recon, and nothing reaches the server without passing your rules. This is the rule we recommend for subdomain_enum_active:
{
"version": "1",
"default": "deny",
"tools": {
"subdomain_enum_active": {
"limits": [
{
"counter": "subdomain_enum_active_rate",
"window": "minute",
"max": 10,
"scope": "grant"
}
]
}
}
}subdomain_enum_active 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.
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Enumerate subdomains using DNS brute force (active reconnaissance). It is categorised as a Execute tool in the MCP Recon MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.
Register the MCP Recon MCP server in PolicyLayer and add a rule for subdomain_enum_active: 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 MCP Recon. Nothing to install.
subdomain_enum_active is a Execute tool with high risk. Execute tools should be rate-limited and have argument validation enabled.
Yes. Add a rate_limit block to the subdomain_enum_active 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.
Set action: deny in the PolicyLayer policy for subdomain_enum_active. 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.
subdomain_enum_active is provided by the MCP Recon MCP server (sundayz-hunter/mcp_recon). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from MCP Recon, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
Free to start. No card required.
13 MCP Recon tools catalogued and risk-classified — across an index of 43,000+ MCP servers.