OurMine, the hacking group behind the hacks of Facebook Inc. founder and Chief Executive Mark Zuckerberg, Google Inc. CEO Sundar Pichai and others, has claimed responsibility for a mass hack of YouTube that it claims is the largest in the site’s history.

The hack, launched on Good Friday, breached thousands of YouTube accounts primarily related to YouTube network Studio 71, which represents numerous YouTube “celebrities” such as RomanAtwoodVlogs, JustKiddingNews and Wranglerstar, along with the channels of a number of prominent right-wing bloggers such as Roaming Millennial.

Each targeted account saw the titles on its videos changed to a message from OurMine, with video descriptions that read, “Hey, it’s OurMine, don’t worry we are just testing your security, please contact us for more information.”

The group said in a statement on its website (link not provided because of malware popups) that “we have no bad intentions and only care about the security and privacy of your accounts and network.”

This isn’t the first time OurMine has targeted YouTube channels. It also claimed responsibility for a hack that targeted Omnia Media channels Kwebbelkop, Vikkstar123, h3h3Productions and EverythingApplePro in a similar attack April 1. According to Powerpxy, that attack saw OurMine gain access to the videos via accessing a YouTube API that allows a third party, in that case Omnia Media, to alter video details, rather than obtain the passwords of individual users themselves.

OurMine has previously claimed responsibility for hacking the Twitter accounts of actor Channing Tatum, Wikipedia co-founder Jimmy Wales, Pokemon Go creator John Hanke and Twitter co-founder Jack Dorsey, as well as directly hacking the websites of both TechCrunch and BuzzFeed.

Hacked accounts have since had their video titles and descriptions restored, though it’s not clear from reports whether this was done by YouTube or OurMine.

Image: OurMine