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Fix Insecure API Management in Fresh

Fresh routes are high-performance, but they are public by default. Insecure API management in Fresh occurs when developers expose sensitive logic in 'routes/api/' without implementing centralized middleware or robust token validation. This allows attackers to bypass frontend logic and hit the backend directly, leading to unauthorized data exfiltration or state manipulation.

The Vulnerable Pattern

import { Handlers } from "$fresh/server.ts";

// routes/api/user_data.ts
export const handler: Handlers = {
async GET(_req, _ctx) {
// VULNERABLE: No authentication or authorization checks
// Sensitive data is exposed to any unauthenticated GET request
const data = { ssn: “123-45-678”, balance: 5000 };
return new Response(JSON.stringify(data), {
headers: { “Content-Type”: “application/json” },
});
},
};

The Secure Implementation

The fix enforces a mandatory Authorization header check using JWT validation. Instead of trusting the request blindly, we use the 'djwt' library to verify the signature of the incoming Bearer token against a server-side secret. In a production Fresh app, this logic should be abstracted into a 'routes/api/_middleware.ts' file to ensure all API sub-routes inherit the security context, preventing 'forgotten' endpoints from remaining public.

import { Handlers } from "$fresh/server.ts";
import { verify } from "https://deno.land/x/djwt/mod.ts";

const key = await crypto.subtle.generateKey({ name: “HMAC”, hash: “SHA-512” }, true, [“sign”, “verify”]);


export const handler: Handlers = {
async GET(req, _ctx) {
const authHeader = req.headers.get(“Authorization”);
if (!authHeader?.startsWith(“Bearer ”)) {
return new Response(“Unauthorized”, { status: 401 });
}


try {
  const jwt = authHeader.split(" ")[1];
  await verify(jwt, key);
  
  const data = { ssn: "***-**-678", balance: 5000 };
  return new Response(JSON.stringify(data));
} catch (err) {
  return new Response("Forbidden", { status: 403 });
}


},
};

System Alert • ID: 2344
Target: Fresh API
Potential Vulnerability

Your Fresh API might be exposed to Insecure API Management

74% of Fresh apps fail this check. Hackers use automated scanners to find this specific flaw. Check your codebase before they do.

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