Unauthorized access to files

Need

Prevention of unauthorized access to files and functionalities

Context

• Requirement of Ruby 2.0 or higher for running the application
• Usage of Rails framework for building web applications

Description

Non compliant code

class UsersController < ApplicationController
  def update
    user = User.find(params[:id])
    user.update(params[:user])
    redirect_to user_path(user)
  end
end

In the above code snippet, we have a UsersController with an update action. This action is responsible for updating user data.

The vulnerability lies in the line user.update(params[:user]). Here, we are directly passing the parameters received from the request to the update method without any sanitization or validation. This is known as Mass Assignment vulnerability.

An attacker can inject potentially dangerous characters or manipulate the parameters in the request to gain unauthorized access to the application or modify data they aren't supposed to. For instance, if the User model has an admin attribute, an attacker could potentially set this attribute to true for their user by simply including it in the request parameters, thereby gaining admin access.

Moreover, if the application is integrated with Sharepoint or any other external system, and if the permissions are not properly configured, this vulnerability could potentially expose access to those systems as well.

Steps

• Implement proper input validation and sanitization to prevent injection of potentially dangerous characters.
• Ensure that only authorized users can access the update functionality.
• Implement proper authorization checks to restrict access to sensitive functionalities and files.
• Consider implementing a file access control mechanism to prevent unauthorized access to files.
• Regularly update and patch the Ruby on Rails framework and its dependencies to address any security vulnerabilities.

Compliant code

class UsersController < ApplicationController
  before_action :set_user, only: [:update]
  before_action :authorize_user, only: [:update]

  def update
    if @user.update(user_params)
      redirect_to user_path(@user)
    else
      render :edit
    end
  end

  private

  def set_user
    @user = User.find(params[:id])
  end

  def authorize_user
    unless current_user == @user || current_user.admin?
      redirect_to root_path, alert: "You are not authorized to perform this action."
    end
  end

  def user_params
    params.require(:user).permit(:name, :email, :password, :password_confirmation)
  end
end

The updated code includes several security measures to prevent unauthorized access and potential injection attacks.

1. Input Validation and Sanitization: The user_params method uses Rails' strong parameters to whitelist acceptable parameters and reject any others. This prevents an attacker from injecting potentially dangerous characters or parameters.

2. Authorization Checks: The authorize_user method checks if the current user is the same as the user being updated or if the current user is an admin. If not, it redirects them to the root path with an alert message. This ensures that only authorized users can update user data.

3. File Access Control: Although not explicitly shown in the code, it is recommended to implement a file access control mechanism at the application level to prevent unauthorized access to files. This could be done using a combination of file permissions, user roles, and access control lists.

4. Regular Updates and Patches: Regularly updating and patching the Ruby on Rails framework and its dependencies can help address any security vulnerabilities that may arise. This is a general best practice and not shown in the code.

5. Set User: The set_user method is a before action that finds the user based on the id parameter. This reduces code duplication and ensures that the user exists before the update action is performed.

References

• 201.Unauthorized access to files