Auth Bypass in Koa with Cockroachdb

An Auth Bypass in a Koa application using CockroachDB typically arises from incorrect session or token handling combined with how database queries are constructed and validated. When authentication logic relies on raw user input to form CockroachDB SQL queries without strict validation, an attacker can manipulate identifiers or tokens to gain unauthorized access.

Consider a Koa route that identifies a user by an ID passed in the URL or a cookie. If the application uses that identifier directly in a CockroachDB query such as SELECT * FROM users WHERE id = $1 and binds the value without verifying that the requesting user is allowed to view that ID, the route may unintentionally expose data or allow privilege escalation. This pattern is often categorized as a BOLA (Broken Object Level Authorization) issue, which is one of the 12 security checks middleBrick runs in parallel.

Another common cause is missing or misconfigured middleware that should enforce authentication on certain endpoints. In Koa, if a route handler is defined without first verifying a session or a valid JWT, the handler executes with the context of the request but without proof that the client is authenticated. When that handler queries CockroachDB for user-specific records, it may return data that should have been restricted, effectively bypassing intended access controls.

Real-world attack patterns such as IDOR (Insecure Direct Object Reference) exploit this by iterating through predictable identifiers and observing differences in responses or error states. middleBrick’s checks include Authentication, BOLA/IDOR, and Property Authorization to detect these gaps. The scanner also cross-references findings with the API specification, including OpenAPI/Swagger 2.0/3.0/3.1 documents with full $ref resolution, to see whether runtime behavior matches declared security requirements.

Additionally, unsafe consumption of user-supplied data in headers, cookies, or JSON payloads can lead to Auth Bypass when the server does not validate the presence or integrity of authentication tokens before querying CockroachDB. For example, if a route reads a token from a header, decodes it, and then uses the decoded user ID in a CockroachDB query without verifying the token signature, an attacker can forge identifiers and gain access to other users’ data.

To secure a Koa application interacting with CockroachDB, enforce strict access controls and parameterized queries. Always validate the requesting user’s permissions before executing database statements, and avoid constructing SQL with string interpolation.

Example: Secure route with user isolation

In this example, the authenticated user’s ID is derived from a verified JWT payload, and CockroachDB is queried using that ID to ensure the request can only access its own data.

const Koa = require('koa');
const Router = require('@koa/router');
const { Pool } = require('pg'); // CockroachDB wire-compatible
const jwt = require('jsonwebtoken');

const app = new Koa();
const router = new Router();
const pool = new Pool({
  connectionString: process.env.DATABASE_URL,
});

// Middleware to verify JWT and attach user context
async function auth(ctx, next) {
  const token = ctx.cookies.get('token') || ctx.header.authorization?.replace('Bearer ', '');
  if (!token) {
    ctx.status = 401;
    ctx.body = { error: 'unauthorized' };
    return;
  }
  try {
    const payload = jwt.verify(token, process.env.JWT_SECRET);
    ctx.state.user = payload; // { sub: 'user-id', scope: 'profile' }
    await next();
  } catch (err) {
    ctx.status = 401;
    ctx.body = { error: 'invalid_token' };
  }
}

// Secure profile endpoint: user can only fetch their own profile
router.get('/profile', auth, async (ctx) => {
  const userId = ctx.state.user.sub;
  const client = await pool.connect();
  try {
    const res = await client.query('SELECT id, email, name FROM users WHERE id = $1', [userId]);
    if (res.rows.length === 0) {
      ctx.status = 404;
      ctx.body = { error: 'not_found' };
      return;
    }
    ctx.body = res.rows[0];
  } finally {
    client.release();
  }
});

// Example of an admin endpoint with role check before querying CockroachDB
router.get('/users/:id', auth, async (ctx) => {
  const requestingUser = ctx.state.user;
  const targetId = ctx.params.id;

  // Ensure the requester has permission to view this resource
  if (requestingUser.sub !== targetId && requestingUser.scope !== 'admin') {
    ctx.status = 403;
    ctx.body = { error: 'forbidden' };
    return;
  }

  const client = await pool.connect();
  try {
    const res = await client.query('SELECT id, email, name, role FROM users WHERE id = $1', [targetId]);
    if (res.rows.length === 0) {
      ctx.status = 404;
      ctx.body = { error: 'not_found' };
      return;
    }
    ctx.body = res.rows[0];
  } finally {
    client.release();
  }
});

app.use(router.routes()).use(router.allowedMethods());

app.listen(3000, () => console.log('Server running on port 3000'));

Key remediation practices

• Use parameterized queries with $1, $2 placeholders to prevent injection and ensure type safety.
• Verify ownership or administrative scope in application logic before querying CockroachDB; do not rely on client-supplied flags.
• Keep authentication middleware separate and ensure it runs before any route handler that accesses the database.
• Restrict token usage to secure, httpOnly cookies or Authorization headers, and validate signatures rigorously.

By combining robust Koa middleware with disciplined CockroachDB access patterns, you reduce the risk of Auth Bypass and align runtime behavior with declared security policies. Tools like middleBrick can validate these configurations through its parallel security checks and OpenAPI/Swagger analysis to help identify mismatches between documented and actual access controls.