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Insecure functionality - Password management

Need​

Secure password management

Context​

  • Usage of C# 7.1 for developing applications with advanced language features and enhancements.
  • Usage of Microsoft.AspNetCore.Mvc for building web applications with ASP.NET Core
  • Usage of Microsoft.AspNetCore.Identity for managing user authentication and authorization in ASP.NET Core applications

Description​

Non compliant code​

public class AccountController : Controller
{
    private readonly UserManager<ApplicationUser> _userManager;

    public AccountController(UserManager<ApplicationUser> userManager)
    {
        _userManager = userManager;
    }

    [HttpPost]
    public async Task<IActionResult> ChangePassword(string userId, string newPassword)
    {
        var user = await _userManager.FindByIdAsync(userId);
        if (user == null)
        {
            return NotFound();
        }

        var token = await _userManager.GeneratePasswordResetTokenAsync(user);
        var result = await _userManager.ResetPasswordAsync(user, token, newPassword);
        if (!result.Succeeded)
        {
            return BadRequest();
        }

        return Ok();
    }
}

In the above code, the ChangePassword method in AccountController is designed to change a user's password. This method accepts two parameters, userId and newPassword, and it uses these parameters to find the user and change their password.

However, the vulnerability lies in the fact that there is no check to ensure that the user making the request is authorized to change the password for the specified user ID. This means that if a malicious user can guess or otherwise obtain another user's ID, they can change that user's password and gain unauthorized access to their account.

This is a serious security vulnerability because it can lead to unauthorized access and potential data breaches. The lack of proper authorization checks in the password change functionality is a common mistake, and it can have serious consequences.

The code should be modified to ensure that the user making the request is the same user that the password is being changed for, or that the user making the request has appropriate permissions to change another user's password.

Steps​

  • Implement proper authentication and authorization mechanisms to ensure that only authorized users can access the ChangePassword functionality.
  • Validate the user's identity before allowing them to change their password. This can be done by verifying their current password or using other secure methods of authentication.
  • Use secure password reset mechanisms, such as sending a password reset link to the user's registered email address, instead of directly changing the password based on user input.
  • Implement strong password policies, including requirements for minimum length, complexity, and expiration.
  • Encrypt and securely store user passwords using a strong hashing algorithm, such as bcrypt or Argon2, to protect them from unauthorized access.
  • Regularly update and patch the application and its dependencies to ensure that any known vulnerabilities are addressed.
  • Conduct regular security audits and penetration testing to identify and fix any potential vulnerabilities in the application.
  • Educate users about the importance of strong passwords and the risks associated with insecure password management practices.

Compliant code​

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

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

    [HttpPost]
    public async Task<IActionResult> ChangePassword(string userId, string currentPassword, string newPassword)
    {
        var user = await _userManager.GetUserAsync(User);
        if (user == null || user.Id != userId)
        {
            return Unauthorized();
        }

        var isCorrect = await _userManager.CheckPasswordAsync(user, currentPassword);
        if (!isCorrect)
        {
            return BadRequest("Current password is incorrect");
        }

        var result = await _userManager.ChangePasswordAsync(user, currentPassword, newPassword);
        if (!result.Succeeded)
        {
            return BadRequest(result.Errors);
        }

        return Ok();
    }
}

The updated code now includes a SignInManager instance which is used to authenticate the user before allowing them to change their password. The ChangePassword method now requires the current password as an additional parameter. This is used to verify the identity of the user before the password change is allowed.

The GetUserAsync method is used to get the currently authenticated user. If the user is not authenticated or the userId does not match the authenticated user's Id, an Unauthorized response is returned.

The CheckPasswordAsync method is used to verify the current password of the user. If the current password is incorrect, a BadRequest response is returned with an appropriate error message.

The ChangePasswordAsync method is used to change the user's password. If the password change fails (for example, due to password complexity requirements), a BadRequest response is returned with the error details.

This approach ensures that only authenticated users can change their own passwords, and that they must verify their identity by providing their current password before the change is allowed. This significantly reduces the risk of unauthorized password changes.

References​

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