Need

Protection of sensitive information in metadata files

Context

• Usage of C# for building robust and scalable applications
• Usage of System for accessing and manipulating system-level functionalities
• Usage of Microsoft.AspNetCore.Mvc for building web applications with ASP.NET Core

Description

Non compliant code

        using System;
using Microsoft.AspNetCore.Mvc;

namespace VulnerableApp.Controllers
{
    public class UserController : Controller
    {
        [HttpGet]
        public IActionResult GetUserData()
        {
            var user = new
            {
                Name = "John Doe",
                Email = "john.doe@example.com",
                Password = "password123", // Sensitive data
                Address = "123 Main St, Anytown, USA"
            };

            return Ok(user);
        }
    }
}
        
        

The above code represents a controller in an ASP.NET Core application that exposes sensitive user data. The GetUserData method is a HTTP GET endpoint that returns a user object with sensitive data like email and password.

The user object is created with hard-coded data for the sake of example. In a real-world application, this data would likely be fetched from a database or another data source.

The problem here is that the password, which is sensitive information, is included in the object that's returned by the endpoint. This means that anyone who can access this endpoint can also access the user's password. This is a serious security vulnerability, as it could allow an attacker to gain unauthorized access to the user's account.

The vulnerability could be exploited by an attacker simply by sending a GET request to the GetUserData endpoint. The response to this request would include the user's password, along with other user data.

To fix this vulnerability, sensitive data like passwords should never be included in the data that's sent from the server to the client. Instead, passwords should be stored securely on the server, and they should never be transmitted over the network.

Steps

• Avoid exposing sensitive information in public metadata files.
• Remove the sensitive data from the response returned by the 'GetUserData' action.
• Consider storing sensitive data securely, such as using encryption or hashing.
• Implement proper authentication and authorization mechanisms to protect sensitive data.
• Ensure that access to sensitive data is restricted to authorized users only.
• Regularly review and update the application's security measures to address any potential vulnerabilities.

Compliant code

        using System;
using Microsoft.AspNetCore.Mvc;

namespace VulnerableApp.Controllers
{
    public class UserController : Controller
    {
        [HttpGet]
        public IActionResult GetUserData()
        {
            var user = new
            {
                Name = "John Doe",
                Email = "john.doe@example.com",
                Address = "123 Main St, Anytown, USA"
            };

            return Ok(user);
        }
    }
}
        
        

The original code was exposing sensitive user information (password) in the response of the GetUserData action. This is a serious security vulnerability as it can lead to unauthorized access and potential data breaches.

The fixed code removes the sensitive data (password) from the response. Now, the GetUserData action only returns the user's name, email, and address. The password is no longer included in the response, thus mitigating the risk of exposing sensitive data.

However, this is just one step in securing the application. Other important steps include:

- Storing sensitive data securely: Sensitive data like passwords should never be stored in plain text. They should be hashed (and salted) before storage. In case of a data breach, hashed passwords are of little use to attackers without the original salt.

- Implementing proper authentication and authorization: Only authenticated and authorized users should have access to sensitive data. Implementing mechanisms like JWT (JSON Web Tokens), OAuth, or sessions can help in this regard.

- Regularly reviewing and updating security measures: Security is not a one-time task but a continuous process. Regularly reviewing and updating security measures can help in identifying and fixing potential vulnerabilities.

References

• 119. Metadata with sensitive information