Sorry, but lack of security isn't one of those problems that comes about with "rapid growth".
However, lack of security IS one of those problems that comes from employing id10ts with zero experience in the real world to build your website.
A quick look at their html source shows it was built with Drupal 7. Also, instead of building a template from the ground up, or even properly tweaking one, they have a tremendous amount of HTML code just commented out... looks like someone didn't exactly know what they are doing and were a little unsure of themselves. Gotta love Kids.
Wonder if they've bothered applying any of the patches...