They've left their ElasticSearch instance naked on the internet, which was found by the researcher using Shodan.
(Current address is another site that blockquotes the majority of the article).
Submitters: we'd appreciate it if you'd check before submitting to make sure an article isn't obviously lifted from some other source. When it is, please submit that source instead. It's the fair thing to do, and also the site rules ask for this: https://news.ycombinator.com/newsguidelines.html.
Edit: actually looks like the original source is a wired.com article that the marketwatch.com article points to. Since there was an earlier submission of that one, we'll merge this thread there.