Federal investigators have taken down a pack of "DDoS-for-hire" services that let buyers knock websites offline for a price.

On Thursday, the US Department of Justice announced it had seized 15 web domains that were selling access to DDoS attacks, but under the guise of network stress-testing services.

The seized domains include critical-boot.com, ragebooter.com, downthem.org and quantumstress.net. In addition, Justice Department has charged three suspects for running two of the DDoS-for-services named.

The services worked by offering customers the ability to launch what's a distributed denial-of-service or DDoS attack, which can overwhelm a website with too much internet traffic, forcing it temporarily offline. Buyers could pay as little as a few dollars a month to $50 or more to gain access to the hacking services, depending on the volume of the attack they wished to launch.

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Gamers like to buy such services to take down opponents in multiplayer games. However, federal investigators claim the 15 DDoS-for-services taken down on Thursday were also used to disrupt access to online platforms from financial institutions, universities, and governments. At least a few of the platforms also had thousands of customers.

"Between October 2014 and November 2018, Downthem's database showed over 2000 customer subscriptions, and had been used to conduct, or attempt to conduct, over 200,000 DDoS attacks," the Justice Department said.

Quantumstress.net, on the other hand, had more than 80,000 customer subscriptions dating back to when the service was first launched in 2012. The FBI is now warning it intends to go after both operators and buyers of such DDoS-for-hire services.

"Whether you launch the DDoS attack or hire a DDoS service to do it for you, the FBI considers it criminal activity," said FBI assistant director Matthew Gorham. "Working with our industry and law enforcement partners, the FBI will identify and potentially prosecute you for this activity."

This article originally appeared on PCMag.com.