Ruby on Rails

Building and Breaking Rails App

http://www.3SLabs.com

• Released to the world as ‘extracted’ from BaseCamp (37Signals) by @dhh during July 2004.

• Merged with Merb Project during December 2008 and Rails 3.0 was released.

• Two supported branch of development currently:– Rails 3.x– Rails 4.x

Acceptance of RoR

.. and LOT more

Building Web Applications using Ruby on Rails

RoR Application Structure

Image Source: http://blog.ifuturz.com/ruby-on-rails/ruby-on-rails-mvc-learn-with-fun.html

Building a RoR App

1. Ruby & Ruby Gem Installation2. Generate RoR Project3. Design ERD4. Generate Scaffolds5. Define Relationships6. Create Database Schema7. Start Application Server

RoR: Web Blog Example

Our Blog is a web application where one or more Users can self-register and sign-in using their registered credentials.

Upon sign-in each User should be able to publish Blog Post that is visible to any user or visitor of the portal.

Any User or Visitor of the portal should optionally Comment on any Blog Post.

RoR: Web Blog ERD

Step1: Generate Project

Step2: Generate Scaffolds

Step3: Setup Database Schema

Step4: Launch App Server

http://m.xkcd.org/844/

Now write some code or customize the views..

After some love of Bootstrap3

Learning Ruby on Rails

• Ruby on Rails Official Guide– http://guides.rubyonrails.org/

• Agile Web Development with Rails– http://pragprog.com/book/rails4/agile-web-development-with-rails

• Ruby on Rails Podcasts– http://podcast.rubyonrails.org/

• Rails Code School– https://www.codeschool.com/courses/rails-for-zombies-redux

• Rails Cast– http://railscasts.com/

Breaking Ruby on Rails Applications

Image (Karate) by Nicholas Riggle from The Noun Project CC By 2.0

Penetration Testing Rails App

• Black/Gray Box Approach– Conventional Testing– Fingerprinting Rails Framework– Rails specific Vulnerability Testing– Rails specific Weakness Testing

• White Box Approach– Automated Scan for known Vulnerabilities

• Brakeman– Attack Surface enumeration through Routes– Authentication & Authorization Testing– Common Rails information disclosures (secret_token.rb)– Model Attributes Security– Custom/Unconventional SQL Queries Audit– Responsive View Audit

Fingerprinting Rails Applications

• No generic and definitive technique!– It’s a cat & mouse game really.

• Heuristics– Session Identifier– Asset Pipeline– [ … ]

Fingerprinting Rails Application

Not so easy for an application served with a reverse proxy which is almost always the case in production.

Fingerprinting Rails Application

Leveraging the assets pipeline which is enabled by default from Rails 3.1

Automated Testing: Brakeman

http://brakemanscanner.org/

Need source code access !

Automated Testing: grep(1)

eval

instance_eval class_eval

DRb.start_server

find_by_sql

system exec

popen

You will be surprised to see how effective this is !

/`(.*)`/

Attack Surface: Routes

Attack Surface: Routes

• Default Routing– <Resource> is handled by app/controllers/<resources>_controller.rb– CRUD on Resource

Session Security

• A whole set of attacks are possible on Session Management functionality of any Web Application.– Session Hijack, Session Fixation, Session Id Prediction, Session Data

Tampering, Leveraging Session Data for RCE etc.

• Rails provide inbuilt Session Management– The session object is available to application developer as

a Hash/Map to store arbitrary data.– The session object is serialized and stored in

corresponding session storage as per configuration.– Signed cookie is used for session storage by default.

Session Security

http://robertheaton.com/2013/07/22/how-to-hack-a-rails-app-using-its-secret-token/

Not a Good idea !

Session Security: Best Practices

Enforce SSL in order to avoid sniffing of session id

Re-generate session after authentication to avoid session fixation

Store session in database instead of Cookie which is default

Cookie based Session Store are susceptible to Replay Attacks

Authentication

• Multiple Popular Authentication Plugin– Devise– RESTful Authentication– […]

• Devise– Auto-generated Registration, Confirmation, Login,

Forgot Password etc.– Controller filter for enforcing authentication.

Testing Authentication

• Generic Issues– Weak Session Management– Weak Authentication Enforcement– Weak Password Encryption

• Plugin/Gem Specific– Devise Vulnerabilities– Lack of Authentication Enforcement– Timing Attacks– Information Gathering through default message

Are all controllers protected by Authentication System?

Authorization

• Not provided by default in the framework.– Encourages RESTful design.• Easy to implement RBAC on Resources

– Multiple Gem/Plugin available

Example usage of CanCan for Authorizationhttps://github.com/ryanb/cancan

Testing Authorization

• Authorization Plugin or Custom Coded?• Every functionality is RESTful?• Query scoping in Controller

Rails CSRF Protection

CSRF Token generation and checking is enforced by default.

• Application must use Rails Form Tag Helps to generate forms rather than HTML directly.

• HTTP GET is not protected !

Killing Rails CSRF Protection

http://blog.codeclimate.com/blog/2013/03/27/rails-insecure-defaults/

Rails Model Security

• The Business Logic Layer– Database Abstraction through ORM– Entity Relationship Definition– Business Logic

• Common Security Issues– Attribute Mass Assignment

• Mitigated by default in newer version of Rails

– Custom (insecure) SQL Queries– Business Logic Vulnerabilities

Rails Model: Attribute Mass Assignment

The Model

The Controller

The Malicious Input

Rails Model: SQL Queries

Model Scope

Chained Query Interface (ActiveRelation)

Parameterized Qury

Rails Model: Insecure SQL Queries

The application developer should ensure that the Query Interface understand the difference between Query and Data.

Rails Model: SQL Injection Vectors

• ActiveRecord does not escape parameters for certain options:

Source: http://rails-sqli.org/

View Rendering

• Dynamic parameters are encoded by default unless explicitly marked as safe.

• There are scope for Reflected XSS– Strings marked explicitly with html_safe method.– Textile/Markdown Injection– Insecure used of content_tag

Secure Headers

• Rails 3.x is vulnerable to Clickjacking & UI Redressing Type of attacks in default configuration.– Easy Mitigation• gem ‘secureheaders’ in Gemfile

– https://github.com/twitter/secureheaders

Rails: Framework Vulnerabilities

http://www.cvedetails.com/vulnerability-list/vendor_id-12043/product_id-22568/Rubyonrails-Ruby-On-Rails.html

References

• Ruby on Rails Security Guide– http://guides.rubyonrails.org/security.html

• Brakeman Scanner– http://brakemanscanner.org/

• Rails SQLi Examples– http://rails-sqli.org/

• OWASP Cheatsheet for RoR– https://www.owasp.org/index.php/Ruby_on_Rails_Cheatsheet

• Ruby Security Configuration– http://blog.codeclimate.com/blog/2013/03/27/rails-insecure-defaults/

• Ruby Mechanize– http://mechanize.rubyforge.org/

• Ruby Nokogiri– http://nokogiri.org/

• The Noun Project– http://thenounproject.com/