Broken Access Control in Rails with Cockroachdb

Broken Access Control in a Ruby on Rails application using CockroachDB as the backend database often stems from application-layer authorization logic rather than database-specific behavior. However, the way data is modeled, queried, and scoped in CockroachDB can inadvertently enable or amplify access control weaknesses when those queries are constructed without proper constraints.

Consider a multi-tenant SaaS application where each Account has many Projects and users belong to accounts via memberships. A typical vulnerable controller might load a project like this:

class ProjectsController < ApplicationController
  def show
    @project = Project.find(params[:id])
    # No check that current_user is a member of @project.account
  end
end

If the Project model scope does not enforce tenant isolation at the query level, an attacker can manipulate the ID to access projects belonging to other accounts. With CockroachDB, which provides strong consistency and serializable isolation by default, the query will reliably return data if a row exists—even across tenant boundaries—if the application does not append an account_id filter. This means a horizontally escalated IDOR (Insecure Direct Object Reference) becomes effective and deterministic, unlike some databases where race conditions or eventual consistency might obscure the issue.

Additionally, CockroachDB’s support for complex SQL features such as window functions and full-text indexes can encourage developers to write richer queries that inadvertently expose relationships. For example, a join that pulls user roles from an associated table may be used to infer administrative status if the authorization check is performed in Ruby instead of in the database constraint or scope. Insecure Direct Object Reference (IDOR), a specific manifestation of Broken Access Control, is therefore not a CockroachDB flaw but a consequence of missing scoping that CockroachDB’s reliable consistency can make more apparent during testing and audits.

Another vector arises in APIs that expose search or filter endpoints. If query parameters are mapped directly to database columns without strict allow-listing, an attacker can use crafted filters to access records they should not see. Because CockroachDB adheres closely to SQL standards, parameterized queries that lack proper row-level security predicates will consistently return sensitive rows, making the exposure repeatable and easier to exploit.

To mitigate Broken Access Control when using CockroachDB with Rails, enforce tenant and ownership checks at the model and query level. Always scope records by the current user’s context and avoid relying on controller-level checks alone.

Use a default scope or a concern that automatically adds the tenant constraint. For example, with a current_account method available via authentication:

class Project < ApplicationRecord
  belongs_to :account
  belongs_to :owner, class_name: 'User'

  # Ensures every query includes account_id unless explicitly unscoped
  default_scope { where(account_id: Current.account&.id) }

  # Alternatively, use a concern for multi-tenant scoping
  # include TenantScoped
end

In your controller, combine the default scope with an explicit authorization check for defense in depth:

class ProjectsController < ApplicationController
  before_action :set_project, only: [:show, :edit, :update, :destroy]
  before_action :authorize_project_access, only: [:show, :edit, :update, :destroy]

  def show
    # @project is already scoped by default_scope
  end

  private

  def set_project
    @project = Project.find_by(id: params[:id])
  end

  def authorize_project_access
    return if @project && current_user.member_of?(@project.account)
    redirect_to root_path, alert: 'Not authorized'
  end
end

If you prefer explicit joins to verify membership without relying solely on default scopes, write a query that CockroachDB can execute safely with proper indexes:

class Project < ApplicationRecord
  def self.accessible_by_user(user)
    joins(:account, :memberships).where(
      memberships: { user_id: user.id },
      accounts: { id: user.account_ids }
    )
  end
end

# Usage in controller
@projects = Project.accessible_by_user(current_user)

For APIs that accept filter parameters, sanitize and restrict the keys that can be used in WHERE clauses. Avoid passing raw user input directly to where:

allowed_filters = %w[name status]
filters = params.slice(*allowed_filters)
@projects = Project.accessible_by_user(current_user).where(filters)

Finally, leverage Rails’ built-in mechanisms like Pundit or a custom policy object to centralize authorization logic, ensuring that every data access path respects the same rules regardless of how records are retrieved from CockroachDB.