Introduction

Securing your application’s Firestore database is crucial for protecting sensitive data and maintaining user trust. Google Firestore, a scalable NoSQL cloud database, offers robust features for real-time data management, but securing it against threats requires careful attention.

This article is designed to help developers and security professionals assess and strengthen their Firestore implementations. A white box approach involves having access to Firestore database rules.

Use Case and Goal

Whether you are developing a mobile app, a web platform, or any cloud-based service using Firestore, ensuring your database is secure is essential. The goal of this review is to provide a checklist covering key areas such as Authorization and ACLs, Data Validation, Cloud Functions, Authentication Methods, Sensitive Data Management, and Logging and Monitoring. By following these guidelines, you can safeguard your Firestore setup against unauthorized access, data breaches, and other security risks.

Audience

This guide is tailored for security professionals and developers involved in securing applications that use the Firestore database. This article offers technical examples to help you verify security measures effectively. Whether you’re new to Firestore or looking to enhance your existing security settings, this article equips you with the knowledge to build resilient and trustworthy applications.

Dive in to explore essential security practices and technical strategies that will fortify your Firestore databases, ensuring they remain secure and reliable in today’s interconnected digital environment.

Verification Checklist – High Level

1. Authorization and Access Control Lists (ACL):

• Implement Firestore security rules to manage access to documents and collections.
• Utilize the Firebase Emulator Suite to test security rules.
• Restrict Firestore access strictly to necessary users or services.
• Optimize the use of Firestore roles and permissions.

2. Data Validation:

• Employ security rules for data validation and sanitization.
• Conduct server-side data validation to prevent malicious data from being entered.
• Regularly review and audit document fields for sensitive or extraneous information.

3. Cloud Functions:

• Handle sensitive secrets with care.
• Ensure rigorous input validation.
• Clearly define and manage permissions.
• Catalog and comprehend the functions’ purposes.
• Monitor and adjust timeout and memory allocations.
• Guard against sensitive outputs.

4. Review of Authentication Methods:

• Confirm the correct implementation of Firebase Authentication.

5. Management of Collections with Sensitive Information:

• Thoroughly examine collections containing sensitive data.

6. Logging and Monitoring:

• Activate logging to track access and modifications to the database.
• Establish alerts for any abnormal activities or access patterns.

Verification Checklist – Technical Examples

1. Authorization

• Verifying Security Rules:

  // Example Firestore security rules
  rules_version = '2';
  service cloud.firestore {
    match /databases/{database}/documents {
      // Match any document in the collection 'users'
      match /users/{userId} {
        // Allow read/write access only if the request is from an authenticated user
        allow read, write: if request.auth != null && request.auth.uid == userId;
     }
    }
  }

2. Security Rules Configuration

• Controlling Access with Security Rules:

  // Allow read access to a document if the user's role is 'admin'
  match /someDocument/{docId} {
    allow read: if get(/databases/$(database)/documents/users/$(request.auth.uid)).data.role == 'admin';
  }

• Data Validation with Security Rules:

  // Validate data structure for a 'posts' collection
  match /posts/{postId} {
    allow create: if request.resource.data.keys().hasAll(['title', 'content', 'authorId'])
                  && request.resource.data.title is string
                  && request.resource.data.content is string;
  }

• Testing Security Rules with Firebase Emulator:

  # Install Firebase CLI and start the emulator
  npm install -g firebase-tools
  firebase init emulators
  firebase emulators:start

3. Data Validation

• Server-side Data Validation:

  // Validate a new post object in a Cloud Function
  exports.validatePost = functions.firestore
    .document('posts/{postId}')
    .onCreate((snapshot, context) => {
      const post = snapshot.data();
      if (!post.title || !post.content) {
        // Invalid data, handle accordingly
     }
      // Continue with processing
    });

4. Access Control

• Limiting Firestore Access:

  // Firestore security rule to limit access
  match /restrictedCollection/{docId} {
    allow read, write: if request.auth.uid in ['list', 'of', 'authorized', 'userIds'];
  }

• Using Firestore Roles and Permissions:

  // Firestore security rule using custom user roles
  match /someCollection/{docId} {
    allow read, write: if get(/databases/$(database)/documents/users/$(request.auth.uid)).data.role == 'admin';
  }

5. Logging and Monitoring

• Setting Up Alerts:

  // Example: Set up a Custom Cloud Function to monitor unusual activities
  exports.detectUnusualActivity = functions.firestore
    .document('someCollection/{docId}')
    .onWrite((change, context) => {
      // Analyze change patterns and set up alerts
    });

6. Authentication

1. Access Firebase Console:

• Go to the Firebase Console.
• Select your project.

2. Navigate to the Authentication Section:

• In the Firebase Console, locate and click on the “Authentication” tab on the left sidebar.

3. Select the Sign-in Method Tab:

• Inside the Authentication section, go to the “Sign-in method” tab.

4. Enable/Configure Authentication Providers:

• Here, you will find a list of authentication providers like Email/Password, Google, Facebook, Twitter, GitHub, etc.
• Click on each provider to configure and enable them.
  • For Email/Password: Simply enable it if you want to allow users to sign up using their email addresses and passwords.
  • For Social Providers (like Google, Facebook, etc.): You will need to provide the app-specific credentials (like App ID and App Secret for Facebook).
  • For Anonymous Authentication: You can enable this if you want to allow users to sign in anonymously.