Broken Access Control in Sinatra with Cockroachdb

Broken Access Control occurs when an API fails to enforce proper authorization checks between subjects (users or services) and resources. In a Sinatra application that uses Cockroachdb as the backend, the risk is amplified when route handlers construct SQL queries using insufficient context about the authenticated subject’s permissions.

Consider a typical pattern where a Sinatra route identifies a resource by an identifier provided in the URL (for example, /users/:id). If the handler builds a Cockroachdb query by directly interpolating that identifier without first confirming that the requesting user has the right to view or modify the resource, an Insecure Direct Object Reference (IDOR) / Broken Object Level Authorization (BOLA) exposure occurs. An attacker can change the identifier to access another user’s data, and because Cockroachdb returns rows based purely on SQL filters, the database will respond with data the application layer did not intend to expose.

Another common scenario involves privilege escalation when role or scope information is stored in Cockroachdb but not validated on each request. Sinatra middleware might read a user record from Cockroachdb at login and store a role in the session, but if subsequent endpoints rely only on that cached role without rechecking database-level constraints (such as tenant_id or admin flags), an attacker can manipulate client-side state to gain elevated access. Because Cockroachdb is strongly consistent, an attacker who can modify their own row via an insecure endpoint might immediately see the effects, enabling lateral movement across tenant boundaries.

Input validation gaps compound these issues. When parameters bound to Cockroachdb queries are not strictly validated, attackers can use crafted inputs to trigger authorization logic bugs, such as bypassing intended filters or causing information leakage through error messages. Since Sinatra routes often map closely to business objects, missing authorization checks in one endpoint can imply broader exposure across the API surface, especially when the Swagger/OpenAPI spec does not accurately reflect the required scopes or relationships enforced by Cockroachdb policies.

To detect these patterns, middleBrick scans unauthenticated attack surfaces and correlates OpenAPI/Swagger definitions with runtime behavior. It flags endpoints where identifiers are accepted without verifying that the caller’s subject matches the resource’s ownership or tenant context, and highlights missing authorization checks that could lead to IDOR or privilege escalation. The scanner also inspects LLM endpoints for system prompt leakage and prompt injection, which is a unique capability when AI features are integrated into the API surface.

Secure remediation centers on enforcing ownership and scope checks in every handler that interacts with Cockroachdb, and never trusting client-supplied identifiers alone. Below are concrete, realistic code examples that demonstrate how to implement these checks correctly.

First, always bind the subject’s identity (for example, current_user_id) to the query rather than relying on URL parameters for access decisions. Using placeholders ensures that Cockroachdb filters at the database level and prevents accidental exposure of other rows.

# Safe Sinatra route with Cockroachdb ownership check
require 'sinatra'
require 'pg' # Cockroachdb wire-compatible driver

before do
  content_type :json
end

helpers do
  def current_user
    # In practice, derive this from your auth mechanism (e.g., JWT)
    @current_user ||= { id: 1, role: 'user', tenant_id: 'acme' }
  end

  def db
    @db ||= PG.connect(ENV['DATABASE_URL'])
  end
end

get '/users/:user_id/profile' do
  user = current_user
  target_id = params['user_id']

  # Enforce ownership at the query level
  result = db.exec_params('SELECT id, name, email FROM profiles WHERE id = $1 AND tenant_id = $2', [target_id, user[:tenant_id]])

  if result.ntuples == 1
    result[0].to_hash
  else
    status 404
    { error: 'Not found or access denied' }.to_json
  end
end

This pattern ensures that even if an attacker manipulates :user_id, Cockroachdb will only return rows where both the ID and tenant match the authenticated subject. The query uses parameterized statements to avoid injection and embeds tenant context to prevent cross-tenant reads, a critical control in multi-tenant applications.

For endpoints that modify data, repeat the ownership or scope verification before executing writes. Do not rely on client-supplied flags or prior session state alone.

# Safe update with scope and role checks
put '/users/:user_id/status' do
  user = current_user
  target_id = params['user_id']
  new_status = params['status']

  # Ensure the caller is allowed to update this user
  check = db.exec_params('SELECT role, tenant_id FROM users WHERE id = $1', [user[:id]]).first
  unless check && (check['role'] == 'admin' || check['tenant_id'] == user[:tenant_id])
    status 403
    { error: 'Forbidden' }.to_json
  end

  # Apply update with tenant-aware filter
  res = db.exec_params('UPDATE users SET status = $1 WHERE id = $2 AND tenant_id = $3', [new_status, target_id, user[:tenant_id]])

  if res.cmd_tuples == 1
    { status: 'updated' }.to_json
  else
    status 404
    { error: 'Not found or access denied' }.to_json
  end
end

These examples show how to integrate Cockroachdb checks directly into Sinatra routes, combining application-level identity with database-level filters. By validating scope on every relevant request and using parameterized queries, you reduce the window for IDOR and privilege escalation. middleBrick’s scans can then verify that such controls are present in both the spec and runtime behavior, providing prioritized findings with remediation guidance.

When using the middleBrick CLI, you can run middlebrick scan <url> to evaluate these endpoints. Teams on the Pro plan can enable continuous monitoring and CI/CD integration to catch regressions early, while the Web Dashboard helps track security scores over time.