While searching through the web I also saw the gem brakeman. It analyses your Ruby on Rails application for possible security vulnerabilities. It also assigns confidence level to each warning to indicate how certain the tool that it is actually a problem. It doesn’t generate a comprehensive security report about your rails app but it’s a good tool to check common vulnerabilities. The Open Web Application Security Project (also known as OWASP) also has a quick cheat sheet for securing your Rails application.