Ruby on Rails Security: Build Secure Web Apps

Security is not a feature you add at the end. It belongs at the core of every web app. At Wolfpack Digital, we build with data privacy, app security, and clean code in mind from day one.

We asked Florin, our Head of Web Development, for his best tips. Here is his practical guide to Ruby on Rails security, based on years of building fintech and healthcare apps.

Why web application security matters

A single breach can cost trust, money, and data. Strong web application security protects your users and your business. Rails helps here, since it ships with sensible, secure defaults.

Still, defaults are only a start. The steps below show how to harden a Rails app in practice.

How to build secure web apps with Ruby on Rails

1. Use HTTPS and SSL certificates

Serve every page over HTTPS. Add a Secure Sockets Layer (SSL) certificate to encrypt the connection. This protects data in transit and builds trust with your users.

2. Add a CDN and firewall like Cloudflare

A service like Cloudflare boosts both speed and security. It caches content at data centers worldwide, so visitors connect to a nearby server.

The result is faster load times and lower bandwidth use. It also shields your app from malicious traffic, DDoS attacks, and other threats.

3. Sanitize user input

Every app exchanges data between users and the server. Most users are honest. But some may send malicious or unauthorized data to cause harm.

Sanitizing input means checking it against clear rules before you trust it. Pair sanitization with validation for defense in depth. Together, they keep bad data out of your app.

4. Prevent SQL injection

SQL injection lets an attacker tamper with your database through unsafe input. It can bypass authorization and expose your data.

To prevent it in Rails, use dynamic, attribute-based finders. Never build queries from raw strings. Rails also escapes strings automatically and gives you a sanitize helper, so you can allow only the tags you trust.

5. Whitelist your parameters

Humans forget things. A blacklist only blocks the bad inputs you remember at the time. A whitelist flips this around: it allows only what you explicitly approve.

Rails uses strong parameters for exactly this. Permit only the fields your action needs, and reject everything else by default.

6. Secure your tokens and cookies

Most apps now use token-based authentication. A token is encoded and checked on each request, without storing user data server-side. Give every token a set lifetime, and support expiry and deactivation.

If you use session-based authentication instead, encrypt the session data. Either way, never leave credentials in plain text.

7. Hash and salt passwords with bcrypt

Passwords must never be stored as plain text. Hashing turns a password into a fixed-length value that cannot be reversed. Salting adds random data to each password first, so identical passwords produce different hashes.

Rails ships with the bcrypt gem for this. It handles setting, salting, hashing, and authenticating passwords with little effort.

8. Keep secrets out of your code

Never hard-code third-party credentials or other sensitive data. Store them as environment variables, or keep them encrypted with Rails credentials.

Stay current with Rails security updates

Security is ongoing work. Keep your framework and gems up to date. The current stable version is Rails 8.1, running on modern Ruby, and each release brings security fixes worth applying.

Tools like bundler-audit and Brakeman scan your app for known issues. Run them often as part of your workflow.

Build a secure Rails app with Wolfpack Digital

These are just the basics. For a deeper dive, read the official Securing Rails Applications guide. You can also learn why we choose Ruby on Rails for web app development.

Want a secure app built for you? We guide you through the full development process, from strategy to launch. Curious about Rails on mobile? See our take on mobile apps with Ruby.

Get in touch, and let's build something secure together.