Bola Idor in Koa with Cockroachdb

Broken Object Level Authorization (BOLA) occurs when an API exposes direct object references (IDs) without verifying that the requesting user is authorized to access the targeted resource. Using Koa with CockroachDB can inadvertently create or expose BOLA when route parameters such as :id are bound directly to database queries without contextual authorization checks. Because CockroachDB is a distributed SQL database that presents logical tables much like a traditional relational store, developers often write straightforward SQL like SELECT * FROM accounts WHERE id = $1 and bind the URL parameter id without confirming that the authenticated subject (e.g., a user or service) owns or is permitted to view that specific row.

In a typical Koa controller, a missing ownership or tenant check turns a simple lookup into an authorization bypass. For example, an endpoint like GET /api/users/:id might execute SELECT id, name, email FROM users WHERE id = $1 using the id from params. If the API relies only on path-level authentication (e.g., an API key or session) and does not enforce that the authenticated user’s identity matches the requested id, an attacker can enumerate numeric or UUID identifiers and read other users’ data. CockroachDB’s strong consistency and SQL semantics do not prevent this; the vulnerability stems from the application logic, not the database itself. Common patterns that exacerbate the issue include using sequential IDs in URLs, failing to scope queries by tenant or user context, and assuming that transport-layer security (TLS) or authentication middleware is sufficient to enforce per-object permissions.

Moreover, when using joins or secondary indexes across tables (e.g., linking user profiles to settings or roles), a missing row-level scope allows horizontal privilege escalation. An attacker who guesses or iterates IDs might traverse relationships that the Koa routes expose indirectly, such as /api/teams/:teamId/members/:userId, where neither teamId nor userId is validated against the requester’s permissions. Because CockroachDB supports complex queries and foreign-key relationships, developers may inadvertently expose more data than intended when constructing SQL without explicit ownership predicates. The risk is amplified in microservice or multi-tenant architectures where a single CockroachDB cluster serves multiple logical domains, and the application layer must enforce strict tenant and object boundaries.

Real-world attack patterns mirror the OWASP API Top 10 A1: Broken Object Level Authorization, often cataloged with references to generalized IDOR vectors. In practice, this means that an unauthenticated or low-privilege attacker can manipulate the :id path segment to access resources such as financial records, personal identifiable information, or administrative configurations. Because the API surface is unauthenticated for scanning purposes, tools like middleBrick can detect these flaws by probing endpoints with varying identifiers and observing whether unauthorized data is returned, highlighting the need for explicit object-level checks in Koa handlers backed by CockroachDB.

To mitigate BOLA in Koa with CockroachDB, enforce object-level authorization by scoping every query to the requester’s identity or tenant. Instead of using raw IDs from the route alone, bind the authenticated subject’s identifier (e.g., user ID or tenant ID) into the WHERE clause. Below are concrete, syntactically correct examples that demonstrate secure patterns.

Example 1: User-specific data access

Ensure that each request to a user-centric endpoint includes the authenticated user’s ID both in the route (for readability) and in the database predicate. Do not trust the route parameter alone; validate it against the session or token subject.

// controllers/userController.js
const getCurrentUser = async (ctx) => {
  const userId = ctx.state.user.id; // authenticated subject from auth middleware
  const paramId = ctx.params.id;

  if (userId !== paramId) {
    ctx.status = 403;
    ctx.body = { error: 'Forbidden: insufficient permissions' };
    return;
  }

  const query = 'SELECT id, name, email FROM users WHERE id = $1 AND tenant_id = $2';
  const values = [userId, ctx.state.user.tenantId];
  const { rows } = await ctx.db.query(query, values);

  if (rows.length === 0) {
    ctx.status = 404;
    return;
  }
  ctx.body = rows[0];
};

Example 2: Tenant-scoped access with CockroachDB

In multi-tenant setups, always include the tenant identifier in the SQL predicate. Use a composite index on (tenant_id, id) for performance and safety, and ensure the route parameter is only used as an additional filter, not as the sole access mechanism.

// controllers/tenantController.js
const getTenantResource = async (ctx) => {
  const { resourceId } = ctx.params;
  const { tenantId } = ctx.state.user; // from auth context

  const sql = 'SELECT id, name, config FROM resources WHERE id = $1 AND tenant_id = $2';
  const values = [resourceId, tenantId];
  const { rows } = await ctx.db.query(sql, values);

  if (!rows.length) {
    ctx.throw(404, 'Resource not found or access denied');
  }
  ctx.body = rows[0];
};

Example 3: Safe parameterized queries with placeholders

Always use parameterized queries to avoid injection and ensure that identifiers are properly typed. CockroachDB’s wire protocol supports placeholders like $1, $2, which align with node-postgres-style drivers used in Koa applications.

// db/connection.js — example setup
const { Pool } = require('pg');
const pool = new Pool({
  connectionString: process.env.DATABASE_URL,
  ssl: { rejectUnauthorized: false },
});

module.exports = pool;

// controllers/accountController.js
const pool = require('../db/connection');

const getAccount = async (ctx) => {
  const accountId = ctx.params.accountId;
  const userId = ctx.state.user.id;

  const sql = 'SELECT account_id, balance FROM accounts WHERE account_id = $1 AND owner_id = $2';
  const values = [accountId, userId];
  const { rows } = await pool.query(sql, values);

  if (!rows.length) {
    ctx.status = 403;
    ctx.body = { error: 'Access to this account is not allowed' };
    return;
  }
  ctx.body = rows[0];
};

These patterns ensure that object-level checks are performed consistently, reducing the attack surface for BOLA. Combine these coding practices with regular scans using middleBrick to validate that endpoints enforce proper scoping and that no unintended data exposure remains. The CLI tool (middlebrick scan <url>) can be integrated into development workflows, while the GitHub Action adds API security checks to your CI/CD pipeline, failing builds if risk scores exceed configured thresholds. For continuous protection, the Pro plan provides ongoing monitoring and alerts, helping maintain secure object boundaries as code evolves.