Guessed weak credentials - C-Sharp

Guessed weak credentials - C-Sharp

Need

Enhancement of credential security

Context

  • Usage of C# 7.1 for developing applications with advanced language features and improvements
  • Usage of Microsoft.AspNetCore.Mvc for building web applications with ASP.NET Core
  • Usage of Microsoft.EntityFrameworkCore for working with databases in .NET applications

Description

Non compliant code

        public class AccountController : Controller
{
    [HttpPost]
    public async Task Login(string username, string password)
    {
        if (string.IsNullOrEmpty(username) || string.IsNullOrEmpty(password))
        {
            return BadRequest();
        }

        var user = await _context.Users.SingleOrDefaultAsync(u => u.Username == username);

        if (user == null)
        {
            return Unauthorized();
        }

        if (user.Password == password)
        {
            // Authenticated successfully
            return Ok();
        }

        return Unauthorized();
    }
}

The above code is a simple login method in an ASP.NET Core application. It takes a username and password as parameters, checks if they are not null or empty, and then tries to find a user in the database with the provided username.

The vulnerability lies in the password comparison part:

                if (user.Password == password)


This means that the system is storing passwords in plain text, which is a major security risk. If an attacker manages to get access to the database, they can easily read all the users' passwords.

Moreover, the system does not enforce any password complexity rules. Users can choose weak passwords, which makes it easier for attackers to guess them through brute force attacks.

Also, the system does not limit the number of login attempts, which means an attacker can keep trying different passwords until they find the correct one.

In summary, this code is vulnerable because it stores passwords in plain text, does not enforce password complexity, and does not limit login attempts.

Steps

  • Implement a strong password policy that enforces complexity requirements such as minimum length, use of uppercase and lowercase letters, numbers, and special characters.
  • Use a secure password hashing algorithm, such as bcrypt or Argon2, to store user passwords instead of storing them in plain text.
  • Implement account lockout mechanisms to prevent brute force attacks, such as locking an account after a certain number of failed login attempts.
  • Implement rate limiting to restrict the number of login attempts per time period from a single IP address or user account.
  • Consider implementing multi-factor authentication (MFA) to provide an additional layer of security.
  • Regularly educate users about the importance of using strong and unique passwords and encourage them to update their passwords periodically.
  • Monitor and log failed login attempts to detect and respond to potential attacks.
  • Conduct regular security assessments and penetration testing to identify and address any vulnerabilities in the authentication system.

Compliant code

        public class AccountController : Controller
{
    private readonly UserManager _userManager;
    private readonly SignInManager _signInManager;

    public AccountController(UserManager userManager, SignInManager signInManager)
    {
        _userManager = userManager;
        _signInManager = signInManager;
    }

    [HttpPost]
    public async Task Login(string username, string password)
    {
        if (string.IsNullOrEmpty(username) || string.IsNullOrEmpty(password))
        {
            return BadRequest();
        }

        var user = await _userManager.FindByNameAsync(username);

        if (user == null)
        {
            return Unauthorized();
        }

        var result = await _signInManager.PasswordSignInAsync(user, password, false, lockoutOnFailure: true);

        if (result.Succeeded)
        {
            // Authenticated successfully
            return Ok();
        }

        return Unauthorized();
    }
}

The updated code now uses ASP.NET Core's built-in UserManager and SignInManager classes, which provide secure password hashing and account lockout mechanisms out of the box.

In the Login method, we first check if the username and password are not null or empty. If they are, we return a BadRequest response.

Next, we use the UserManager to find the user by their username. If the user does not exist, we return an Unauthorized response.

Then, we use the SignInManager to sign in the user with their password. The PasswordSignInAsync method automatically checks if the provided password matches the hashed password stored in the database. If the password is correct, the method returns a SignInResult with Succeeded set to true.

The PasswordSignInAsync method also supports account lockout. If the lockoutOnFailure parameter is set to true, the user's account will be locked out after a certain number of failed login attempts. This helps prevent brute force attacks.

If the login attempt is successful, we return an Ok response. Otherwise, we return an Unauthorized response.

This code does not implement rate limiting, multi-factor authentication (MFA), or logging of failed login attempts. These features would need to be implemented separately. Additionally, user education and regular security assessments are important parts of a comprehensive security strategy.

References