The hacking incident that caused delays in the production of One Piece and Dragon Ball Super: Super Hero was a targeted ransomware attack.
As reported by the NHK, Toei Animation was the target of a ransomware virus that was uploaded onto the studio's private network and servers. Ransomware attacks, especially on large corporations, have become commonplace in the last several years. The viruses work by encrypting or copying key files on company computers or servers, after which the creators of the ransomware then demand a pay-off from their targets in order to remove the encryption or stop those files from being leaked online. The report does not state if Toei paid the ransom, but it does note that the company shut down its internal networks to confirm the existence of the virus and the extent of the damage it had caused.
Toei Animation originally announced on March 6 that its networks were breached by "an unauthorized third party" and that production on several of its biggest projects would be delayed as a result. Several of its most popular anime series, including One Piece, Digimon: Ghost Game, and Dragon Quest: The Adventure of Dai, postponed the release of new episodes and were forced to air rerurns for over a month. The producers of One Piece and Digimon recently announced that they were finally ready to begin broadcasting new episodes on April 17, more than six weeks after those episodes were originally scheduled to air. Crunchyroll has confirmed that it will resume streaming the simulcast of these series' new episodes internationally.
As of the writing of this article, a new premiere date has not been announced for Dragon Ball Super: Super Hero, the latest movie in the long-running shonen franchise. The highly-anticipated film, which is the first movie in the series to be animated entirely using CG, was originally scheduled to be released in Japan on April 22, with a North American premiere following sometime during the summer. The movie's release was indefinitely postponed following the cyber attack, and while Toei has yet to announce a new premiere date, a recent listing for the movie's novelizations suggests that it may now premiere in Japan sometime next June.
Toei is not the only entertainment company to have been the target of this type of hack; most famously, Sony Pictures was the target of a ransomware attack in 2014, in which the hackers reportedly seized over 100 terabytes of private files from the studio. The hackers eventually leaked some of the information they copied and demanded that Sony cancel the release of The Interview, a Seth Rogen comedy about North Korea. Sony eventually did cancel the movie's theatrical run, but released the movie directly through digital distribution services.
Source: NHK via Crunchyroll