Need

Implementation of a strong password policy

Context

• Usage of C# 7.1 for developing applications with advanced language features and improvements
• Usage of Microsoft.AspNetCore.Identity for managing user authentication and authorization in ASP.NET Core applications
• Usage of Microsoft.AspNetCore.Mvc.RazorPages for building web applications with Razor Pages in ASP.NET Core
• Usage of Microsoft.AspNetCore.Mvc for building web applications with ASP.NET Core MVC
• Usage of Microsoft.AspNetCore.Mvc.ViewFeatures for rendering views in ASP.NET Core MVC
• Usage of Microsoft.AspNetCore.Mvc.Abstractions for defining and working with MVC abstractions in ASP.NET Core
• Usage of Microsoft.Extensions.Logging for logging in .NET applications
• Usage of Microsoft.Extensions.Options for managing and accessing configuration options in a .NET application
• Usage of Microsoft.Extensions.DependencyInjection for dependency injection in .NET applications
• Usage of System.Threading.Tasks for asynchronous programming in .NET

Description

Non compliant code

        public class RegisterModel : PageModel
{
    private readonly UserManager _userManager;

    public RegisterModel(UserManager userManager)
    {
        _userManager = userManager;
    }

    public string Password { get; set; }

    public async Task OnPostAsync()
    {
        var user = new IdentityUser { UserName = Input.Email, Email = Input.Email };
        var result = await _userManager.CreateAsync(user, Input.Password);
        if (result.Succeeded)
        {
            return RedirectToPage("/Index");
        }
        else
        {
            foreach (var error in result.Errors)
            {
                ModelState.AddModelError(string.Empty, error.Description);
            }
            return Page();
        }
    }
}
        
        

The above code is an example of a weak credential policy in an ASP.NET Core application. The RegisterModel class is responsible for registering new users into the system. It uses the UserManager class provided by ASP.NET Core for managing users in the system.

The vulnerability lies in the OnPostAsync method, which is responsible for creating a new user. The method takes a password as input and directly uses it to create a new user without any checks for password strength.

This means that a user can register with a weak password, such as "123456" or "password". This makes it easier for an attacker to guess the password and gain unauthorized access to the user's account.

The UserManager.CreateAsync method does not enforce any password policies out of the box. It is the responsibility of the developer to enforce a strong password policy. This can be done by setting the Password property of the PasswordOptions class in the IdentityOptions object, which is used to configure the identity system.

However, in the provided code, no such configuration is made, leading to a weak credential policy vulnerability.

Steps

• Implement a strong password policy that enforces minimum length, complexity, and expiration.
• Use a password hashing algorithm to securely store passwords.
• Implement password strength validation on the client-side to provide immediate feedback to users.
• Consider implementing multi-factor authentication to add an extra layer of security.
• Regularly educate users about the importance of strong passwords and the risks of weak passwords.

Compliant code

        public class RegisterModel : PageModel
{
    private readonly UserManager _userManager;

    public RegisterModel(UserManager userManager)
    {
        _userManager = userManager;
    }

    public string Password { get; set; }

    public async Task OnPostAsync()
    {
        var user = new IdentityUser { UserName = Input.Email, Email = Input.Email };
        var result = await _userManager.CreateAsync(user, Input.Password);
        if (result.Succeeded)
        {
            return RedirectToPage("/Index");
        }
        else
        {
            foreach (var error in result.Errors)
            {
                ModelState.AddModelError(string.Empty, error.Description);
            }
            return Page();
        }
    }
}
        
        

The above code is vulnerable due to weak password policy. The password is accepted without any validation of its strength. This can lead to weak passwords that are easy to guess or crack, leading to unauthorized access.

To fix this vulnerability, we need to enforce a strong password policy. This can be done by setting the Password property in the IdentityOptions class in the ConfigureServices method in the Startup.cs class.

Here is the fixed code:

                public void ConfigureServices(IServiceCollection services)
{
    services.AddIdentity<IdentityUser, IdentityRole>(options =>
    {
        // Password settings
        options.Password.RequireDigit = true;
        options.Password.RequiredLength = 8;
        options.Password.RequireNonAlphanumeric = true;
        options.Password.RequireUppercase = true;
        options.Password.RequireLowercase = true;
        options.Password.RequiredUniqueChars = 6;

        // Lockout settings
        options.Lockout.DefaultLockoutTimeSpan = TimeSpan.FromMinutes(30);
        options.Lockout.MaxFailedAccessAttempts = 10;
        options.Lockout.AllowedForNewUsers = true;

        // User settings
        options.User.RequireUniqueEmail = true;
    })
    .AddEntityFrameworkStores<ApplicationDbContext>()
    .AddDefaultTokenProviders();
}

            

References

• 363. Weak credential policy - Password strength