It sounds like a sci-fi movie. Over 5,000 connected devices, including light bulbs and vending machines, were hacked to slow internet service at a university to a crawl.

Poorly secured internet of things (IoT) devices have become gold mines for hackers looking to launch DDoS attacks to take websites and services offline. But this latest case, detailed in Verizon's Data Breach Digest 2017, is the rare example of gadgets attacking their own network.

SEE ALSO: Your smart fridge is about to make our IoT security nightmare so much worse

The devices were making hundreds of Domain Name Service (DNS) lookups every 15 minutes, causing the university's network connectivity to become unbearably slow or even inaccessible.

Weirdly enough, the majority of the searches "showed an abnormal number of sub-domains related to seafood," the report said.

Here's an abstract from the Digest's sneak peek:

The firewall analysis identified over 5,000 discrete systems making hundreds of DNS lookups every 15 minutes. Of these, nearly all systems were found to be living on the segment of the network dedicated to our IoT infrastructure.

With a massive campus to monitor and manage, everything from light bulbs to vending machines had been connected to the network for ease of management and improved efficiencies.

While these IoT systems were supposed to be isolated from the rest of the network, it was clear that they were all configured to use DNS servers in a different subnet.

Of Botnet and seafood

It's very unlikely, to use an understatement, that thousands of students at the university had a sudden and simultaneous urge to eat seafood.

Instead, what did happen was that cheeky hackers instructed the IoT devices to make DNS lookups related to seafood every 15 minutes.

Here's what Verizon's RISK (Research, Investigations, Solutions and Knowledge) team told the university after they were summoned to investigate the attack:

The RISK Team had provided me with a report detailing known indicators found in the firewall and DNS logs that I had sent over earlier. Of the thousands of domains requested, only 15 distinct IP addresses were returned. Four of these IP addresses and close to 100 of the domains appeared in recent indicator lists for an emergent IoT botnet.

So here's the case of vending machines and lamp posts compulsively searching for seafood and overwhelming the network with requests with the aim of taking it down.

If this isn't creepy/dystopian/fascinating, we don't know what is.

Stopping the wildfire from spreading

Luckily for the guys at the university, there was no need to replace "every soda machine and lamp post".

The Verizon's RISK team explained that the botnet "spread from device to device by brute forcing default and weak passwords".

To solve the massive hack, the university intercepted a clear-text malware password for a compromised IoT device and then used "that information to perform a password change before the next malware update".

Easy, right?

Overall, it doesn't look like this problem is going away anytime soon. There are more than 6 billion IoT devices currently running, according to Gartner Research. That number could reach more than 20 billion by 2020.