Broken Access Control in Grape with Cockroachdb

Broken Access Control occurs when API endpoints fail to enforce proper authorization checks, allowing one user to access or modify another user's resources. Using the Grape framework with Cockroachdb can unintentionally expose this vulnerability when route-level protections are missing and database queries rely only on route parameters without verifying ownership or tenant context.

In a Grape API, developers often define resourceful routes such as GET /users/:id and write Cockroachdb SQL to fetch records by that ID. If the endpoint does not validate that the authenticated user is allowed to view the requested :id, an attacker can change the ID to access other users' data. Cockroachdb’s strong consistency and SQL semantics do not prevent this; the risk comes from the application layer omitting scope checks in the query.

For example, consider a multi-tenant API where accounts are isolated by an account_id. A Grape route that builds a Cockroachdb query like SELECT * FROM documents WHERE id = $1 using only the document ID from the request can lead to Insecure Direct Object References (IDOR), a subset of Broken Access Control. The database returns the record if it exists, regardless of whether the requesting user belongs to the same account. Because middleBrick tests for BOLA/IDOR across OpenAPI specs and runtime behavior, such missing tenant or ownership checks are flagged as high-severity findings.

Additionally, privilege escalation can emerge when role checks are inconsistent between Grape middleware and Cockroachdb row-level security (if used). An endpoint might rely on a user role parsed from a token in Grape but construct a Cockroachdb query that does not filter by role or tenant, returning records that should be restricted. This inconsistency means that even with database-level constraints, the API surface remains vulnerable if the application does not enforce authorization before issuing SQL.

Because middleBrick scans unauthenticated attack surfaces, it can detect endpoints where parameters are directly reflected into Cockroachdb queries without proper authorization, highlighting missing or incomplete access controls in the security report with remediation guidance mapped to frameworks such as OWASP API Top 10 and CIS controls.

To remediate Broken Access Control when using Grape with Cockroachdb, enforce authorization checks in each endpoint and ensure queries always include tenant or ownership filters. Below are concrete, realistic code examples demonstrating secure patterns.

1. Always include tenant or user ownership in WHERE clauses.

# In a Grape resource
class Api::V1::Documents < Grape::API
  format :json
  helpers do
    def current_account
      # Assume a method that resolves account from token or subdomain
    end
  end

  resource :documents do
    desc 'List documents for the current account', secured: true
    get do
      account = current_account
      # Cockroachdb query with tenant isolation
      docs = DB[:documents].where(account_id: account.id).all
      docs
    end
  end
end

2. Verify ownership for item-level access instead of trusting route IDs alone.

class Api::V1::Documents < Grape::API
  resource :documents do
    desc 'Get a document, ensuring ownership', secured: true
    params do
      requires :id, type: Integer, desc: 'Document ID'
    end
    get ':id' do
      account = current_account
      doc = DB[:documents].where(id: params[:id], account_id: account.id).first
      error!('Not found', 404) unless doc
      doc
    end
  end
end

3. Use Cockroachdb row-level security where applicable and keep application-level checks as well.

# Assuming RLS is set up on the table with account_id policy
class Api::V1::Docs < Grape::API
  resource :docs do
    desc 'Safe fetch with RLS-backed query', secured: true
    get do
      # Even with RLS, include account context from the request
      DB[:docs].where(account_id: current_account.id).all
    end
  end
end

4. Avoid dynamic SQL that concatenates identifiers; use parameterized queries to prevent injection and ensure filters are applied correctly.

# Secure parameterized query
stmt = DB[:documents].filter(account_id: current_account.id).filter(id: params[:id]).limit(1)
record = stmt.first
error!('Forbidden', 403) unless record

By combining these patterns, the API ensures that every Cockroachdb query respects authorization boundaries. middleBrick’s scans will then show reduced findings in the BOLA/IDOR and BFLA/Privilege Escalation categories, and the remediation guidance provided in the report can be tracked through the Dashboard or enforced via the GitHub Action in CI/CD.