Need

Enhanced data authenticity validation and enforcement

Context

Description

import UIKit

class ChangePasswordViewController: UIViewController {
    @IBOutlet weak var newPasswordTextField: UITextField!
    
    @IBAction func changePasswordButtonTapped(_ sender: UIButton) {
        let newPassword = newPasswordTextField.text
        if isValidPassword(password: newPassword) {...

The above Swift code for an iOS mobile application represents a ChangePasswordViewController, where users can change their passwords. The password policy in the system is checked in the `isValidPassword(password: String?) -> Bool` function, which uses a regular expression to ensure that the password does not contain consecutive and/or repeated numbers. However, this validation is only performed in the frontend of the application (inside the `changePasswordButtonTapped(_ sender: UIButton)` function), making the system vulnerable. An attacker can bypass this frontend validation by directly making an API call to the `changePasswordAPI(newPassword: String?)` function with a password that violates the system's password policy. To fix this vulnerability, the same password validation should also be performed in the backend of the application, not just the frontend. This ensures that even if the frontend validation is bypassed, the backend validation will still prevent the use of a password that violates the system's password policy.

import UIKit

class ChangePasswordViewController: UIViewController {
    @IBOutlet weak var newPasswordTextField: UITextField!
    
    @IBAction func changePasswordButtonTapped(_ sender: UIButton) {
        let newPassword = newPasswordTextField.text
        changePasswordAPI(newPassword: newPassword)...

The updated code removes the password validation logic from the frontend and moves it to the backend. This is done to prevent a front bypass vulnerability where a malicious user could potentially modify the password from the same request and assign a key that goes against the policies. The `changePasswordButtonTapped` function now directly calls the `changePasswordAPI` function without performing any password validation. The password validation is now expected to be done in the backend. The `changePasswordAPI` function is expected to call a secure API endpoint that changes the user's password. This function should validate the new password using the same validation logic as before (i.e., the password must not be consecutive and/or repeated numbers). If the password does not meet the validation criteria, the backend should return an appropriate error message. The `showError` function is used to display error messages to the user. This function can be used to display the error messages returned by the backend if the password does not meet the validation criteria. By moving the password validation logic to the backend, we ensure that the password validation is always performed, even if a malicious user tries to bypass the frontend validation. This significantly improves the security of the application.

References