RegexMichał

 private void passwordBox_PasswordChanged(object sender, RoutedEventArgs e)
        {
            var hasNumber = new Regex(@"[0-9]+");
            var hasUpperChar = new Regex(@"[A-Z]+");
            var hasLowerChar = new Regex(@"[a-z]+");
            var hasSymbols = new Regex(@"[!@#$%^&*()_+=\[{\]};:<>|./?,-]");

            if(hasNumber.IsMatch(passwordBox.Password))
            {
                Number.Foreground = Brushes.LightGreen;
            }
            else
            {
                Number.Foreground = Brushes.Red;
            }

            if (hasUpperChar.IsMatch(passwordBox.Password))
            {
                BigLetter.Foreground = Brushes.LightGreen;
            }
            else
            {
                BigLetter.Foreground = Brushes.Red;
            }

            if (hasLowerChar.IsMatch(passwordBox.Password))
            {
                SmallLetter.Foreground = Brushes.LightGreen;
            }
            else
            {
                SmallLetter.Foreground = Brushes.Red;
            }


            if (hasSymbols.IsMatch(passwordBox.Password))
            {
               Special.Foreground = Brushes.LightGreen;
            }
            else
            {
                Special.Foreground = Brushes.Red;
            }

        }