dns_update_blocklists

THE RISK

High Risk

Why dns_update_blocklists needs a policy

This tool triggers an external operation (downloading and updating block lists from remote sources) outside the normal 24-hour schedule. It doesn't just read or write local data — it actively pulls external content and applies it to the DNS blocking configuration.

From the tool's definition Force an immediate update of all configured block lists

Risk signalsBulk/mass operation — affects multiple targets

Documented attack patterns abuse exactly the kind of access dns_update_blocklists gives an agent:

POLICY

How to control dns_update_blocklists

PolicyLayer is an MCP gateway — it sits between your AI agents and Technitium MCP Secure, and nothing reaches the server without passing your rules. This is the rule we recommend for dns_update_blocklists:

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "dns_update_blocklists": {
      "limits": [
        {
          "counter": "dns_update_blocklists_rate",
          "window": "minute",
          "max": 10,
          "scope": "grant"
        }
      ]
    }
  }
}

dns_update_blocklists 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.

Create a free account and register Technitium MCP Secure — nothing to install.
Add this policy — paste it, or build it visually.
Point your MCP client (Claude, Cursor, anything) at your gateway URL.

RATE-LIMIT THIS TOOL →

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EXPLORE

Related tools and policies

More Technitium MCP Secure tools

Destructive dns_delete_cached Delete a specific domain from the DNS cache. Unlike flush, this only removes the specified Destructive dns_delete_record Delete a specific DNS record from a zone. Requires confirm=true to execute. Destructive dns_delete_zone Delete a DNS zone and all its records. Requires confirm=true to execute. Destructive dns_remove_allowed Remove a domain from the allow list. The domain will no longer bypass block lists. Destructive dns_uninstall_app Uninstall a DNS app from the server. Requires confirm=true to execute. Destructive dns_flush_allowed Flush the entire allow list. All allowed domains will be removed. Requires confirm=true to Destructive dns_flush_blocked Flush the entire custom block list. All manually blocked domains will be removed. Requires Execute dns_flush_cache Flush the entire DNS cache. Forces all subsequent queries to be resolved fresh from upstre

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Go deeper

High-risk tools in Technitium MCP Secure → Every high-risk tool this server exposes, in one view.
All high-risk MCP tools → Every high-risk tool across the catalogue, and the policy pattern that contains them.
The MCP Attack Database → Documented attack patterns against MCP deployments — and the policies that stop them.
Agent sandbox → Bounding what an agent can execute and where the boundary should sit.
Least privilege for MCP → Granting agents the minimum tool surface the task needs.
Rate Limiting MCP Tool Calls: A Practical Guide →
MCP Security: Why Prompt Guardrails Aren't Enough →

FAQ

Questions about dns_update_blocklists

What does the dns_update_blocklists tool do? +

Force an immediate update of all configured block lists. Normally block lists update every 24 hours. It is categorised as a Execute tool in the Technitium MCP Secure MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.

How do I enforce a policy on dns_update_blocklists? +

Register the Technitium MCP Secure MCP server in PolicyLayer and add a rule for dns_update_blocklists: 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 Technitium MCP Secure. Nothing to install.

What risk level is dns_update_blocklists? +

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

Can I rate-limit dns_update_blocklists? +

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

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

dns_update_blocklists is provided by the Technitium MCP Secure MCP server (rosschurchill/technitium-mcp-secure). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

Enforce policy on every Technitium MCP Secure tool call.

Start from Technitium MCP Secure, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.

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