Luas, Dublin’s tram system, has learned the hard way that ignoring warnings about cybersecurity vulnerabilities isn’t good for business.

On Thursday morning, Lua’s website was defaced. A message left by the hacker read:
You are hacked. Some time ago I wrote that you have serious security holes.
You didn’t reply.
The next time someone talks to you, press the reply button.
You must pay one bitcoin in five days. 
Otherwise I will publish all data and send emails to your users.

In response, Luas took to Twitter to ask people not to visit its site. It then brought the site down in order to deal with the problem. According to Wikipedia, the transit system has a daily ridership of 80,000 passengers.

Experts are mulling the motivations behind the attack. Gizmodo reports, “As far as ransoms go, demanding a single bitcoin is a relatively modest proposal. The current value of one bitcoin is around $3,900. It’s unclear if the hacker is simply being reasonable to give themselves a better chance of getting paid or if they are truly just trying to get the website’s administrators to pay attention to security flaws.”

Get the full story at Gizmodo.