js_read

THE RISK

Low Risk

Why js_read needs a policy

This tool retrieves a single JavaScript file without modifying, executing, or deleting it. It has no side effects beyond accessing data. The context (Burp Suite integration for security testing) reinforces that it is a passive reconnaissance capability.

From the tool's definition Tool name is 'js_read' and description states 'Read one JS file from a source' — the verb 'read' and lack of any modification, deletion, or execution semantics clearly indicate a retrieval operation.

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

POLICY

How to control js_read

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

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "js_read": {}
  }
}

js_read is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.

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

CAP THIS TOOL →

Free to start. No card required.

EXPLORE

Related tools and policies

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Go deeper

The MCP Attack Database → Documented attack patterns against MCP deployments — and the policies that stop them.
Data exfiltration → How read access becomes an exfiltration channel when chained with untrusted content.
MCP token cost → What connecting this server costs in context-window tokens on every request.
Rate Limiting MCP Tool Calls: A Practical Guide →
MCP Security: Why Prompt Guardrails Aren't Enough →

FAQ

Questions about js_read

What does the js_read tool do? +

Read one JS file from a source. It is categorised as a Read tool in the Burp Mcp Plus MCP Server, which means it retrieves data without modifying state.

How do I enforce a policy on js_read? +

Register the Burp Mcp Plus MCP server in PolicyLayer and add a rule for js_read: 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 Burp Mcp Plus. Nothing to install.

What risk level is js_read? +

js_read is a Read tool with low risk. Read-only tools are generally safe to allow by default.

Can I rate-limit js_read? +

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

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

js_read is provided by the Burp Mcp Plus MCP server (titaniumtushar/burp-mcp-plus). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

Enforce policy on every Burp Mcp Plus tool call.

Start from Burp Mcp Plus, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.

CHECK YOUR STACK →