Broken Access Control in Fiber with Basic Auth

Broken Access Control occurs when authorization checks are missing or incorrectly enforced, allowing attackers to access resources or perform actions they should not. In Fiber, using HTTP Basic Authentication without proper role-based or ownership checks can turn a simple convenience feature into a critical security gap. Because Basic Auth only verifies identity (authentication) and does not enforce authorization, developers must explicitly add middleware or logic to restrict endpoints by user role or tenant context. When these checks are omitted, the endpoint becomes vulnerable to BOLA/IDOR and BFLA/Privilege Escalation patterns.

Consider an endpoint that returns user invoices. If the route only validates that a valid username and password are provided, but does not ensure the requesting user can only access their own invoices, any authenticated user can iterate through user IDs and view other accounts’ data. This is a classic case where the combination of Basic Auth and missing authorization checks results in Insecure Direct Object References (IDOR). Attackers can modify numeric or UUID identifiers in the URL to access or manipulate other users’ data without triggering permission denials.

Another scenario involves role-based access where an endpoint should be restricted to administrators. If Basic Auth validates credentials but the handler does not inspect the user’s role, any valid user can invoke administrative operations. This is Privilege Escalation via Missing Authorization. Because Basic Auth transmits credentials encoded but not encrypted unless TLS is used, an attacker who intercepts traffic can also replay credentials to gain unauthorized access. Even when TLS is enforced, endpoints that accept Basic Auth but do not validate scopes or roles remain susceptible to Over-Privileged Accounts and Excessive Agency when integrated with LLM or automation workflows.

During a black-box scan, middleBrick tests unauthenticated attack surfaces where possible and, when Basic Auth is required, evaluates whether authorization checks are consistently applied across similar endpoints. Findings highlight missing checks, inconsistent enforcement, and mappings to OWASP API Top 10 A01:2023 — Broken Access Control. The scanner does not fix these issues; it provides prioritized findings with severity ratings and remediation guidance so teams can add explicit authorization logic and validate ownership on every request.

To secure Fiber endpoints using Basic Auth, combine credential validation with explicit authorization checks. Always enforce TLS in production to protect credentials in transit. Below are two concrete examples showing insecure and secure implementations.

Insecure example — authentication without authorization

const http = require('http');
const jwt = require('jsonwebtoken');

// Insecure: validates Basic Auth but does not enforce per-user or role checks
app.get('/invoices/:id', (req, res) => {
  const authHeader = req.headers.authorization;
  if (!authHeader || !authHeader.startsWith('Basic ')) {
    return res.status(401).send({ error: 'Unauthorized' });
  }
  const base64 = authHeader.split(' ')[1];
  const [user, pass] = Buffer.from(base64, 'base64').toString().split(':');
  if (user !== 'alice' || pass !== 'secret123') {
    return res.status(401).send({ error: 'Invalid credentials' });
  }
  // Missing: check that the invoice belongs to the authenticated user
  const invoiceId = req.params.id;
  const invoice = getInvoiceById(invoiceId); // hypothetical function
  res.json(invoice);
});

This example is vulnerable to IDOR because the handler does not verify that the authenticated user owns the requested invoice ID.

Secure example — authentication plus ownership and role checks

const http = require('http');

// Secure: validate credentials and enforce ownership and role checks
app.get('/invoices/:id', (req, res) => {
  const authHeader = req.headers.authorization;
  if (!authHeader || !authHeader.startsWith('Basic ')) {
    return res.status(401).send({ error: 'Unauthorized' });
  }
  const base64 = authHeader.split(' ')[1];
  const [user, pass] = Buffer.from(base64, 'base64').toString().split(':');
  if (user !== 'alice' || pass !== 'secret123') {
    return res.status(401).send({ error: 'Invalid credentials' });
  }
  // Authorization: ensure the user can only access their own invoices
  const invoiceId = req.params.id;
  const invoice = getInvoiceById(invoiceId);
  if (!invoice) {
    return res.status(404).send({ error: 'Not found' });
  }
  if (invoice.userId !== user) {
    return res.status(403).send({ error: 'Forbidden: you do not own this resource' });
  }
  // Optional: role-based check for admin-only endpoints
  if (invoiceId.startsWith('admin') && user !== 'admin') {
    return res.status(403).send({ error: 'Forbidden: insufficient permissions' });
  }
  res.json(invoice);
});

Additional recommendations include centralizing user identity after Basic Auth validation, using middleware to enforce policies consistently, and integrating findings from scans into your CI/CD pipeline. With middleBrick Pro, you can add continuous monitoring and GitHub Action gates to fail builds if risk scores drop due to missing authorization checks. The MCP Server allows you to scan APIs directly from your AI coding assistant, helping catch these issues earlier in development.