Microsoft Corp.'s Xbox Live and Sony Corp.'s PlayStation Network, Internet services that video gamers use to play online, were hit by connection failures on Christmas Day, with the hackers Lizard Squad claiming responsibility.
Service was restored for Xbox users today, while the PlayStation Network remained offline. Sony said its engineers were "working hard to resolve the network issues."
Hackers attacked the video-game networks on the same day "The Interview" was released online, after major U.S. theaters decided not to show the movie following hacking incidents at Sony's TV and film unit last month. A different group called Guardians of Peace claimed responsibility for infiltrating Sony Pictures Entertainment's servers, destroying data, exposing Hollywood secrets, and forcing the movie studio to cancel the release of the comedy in cinemas. That group and Lizard Squad had threatened further disruptions on Christmas Day.
"It's not yet clear whether it's just an outage of the PlayStation Network or if some personal data has been stolen too," said Hideki Yasuda, a Tokyo-based analyst at Ace Research Institute.
Lizard Squad, which took credit for an attack on Sony earlier this year, said on its Twitter account that it was behind the incidents. The group said it would "stop hitting" the services if users called attention to the hack by retweeting its statements.
"The Interview," a comedy about a fictional assassination of North Korean leader Kim Jong Un, was shown in more than 300 locations on Christmas Day without incident, and was also available for rent and purchase at the Xbox store, a Sony website and Google Play, among others. It topped the charts of the Xbox store and YouTube's movie store. The limited release brought in more than $1 million in ticket sales, Sony Pictures said.
Last week, U.S. President Barack Obama blamed North Korea for orchestrating the attacks against Sony Pictures and vowed to respond. North Korea has said it doesn't know the identity of the hackers claiming responsibility for breaking into Sony's computer network. The country's connection to the Internet was also disrupted earlier this week.
Satoshi Nakajima, a spokesman for Sony's games unit, said the company was investigating whether the attack on the PlayStation Network was related to the Sony Pictures Entertainment hack.
E-mail and voice-mail messages to David Dennis, a spokesman for Redmond, Washington-based Microsoft, weren't returned.
By streaming the comedy via the Web, Microsoft and Sony took the risk of provoking denial-of-service hacking attacks. The hackers had warned that they intended to target the companies with such incidents on Christmas Day.
Denial-of-service assaults can be difficult to deflect, even if a company has ample warning they are coming, because they are executed by thousands of hacked computers performing normal but database-intensive activities, such as performing searches or downloading videos, all at the same time.
Cybercriminals targeted Sony in 2011 after it sued a young researcher when he exposed security vulnerabilities in the PlayStation 3 console. The 2011 hack involved the theft of personal data on 77 million PSN users.
"Last time the network was down for a month and PS4 sales were little affected," Ace Research's Yasuda said. "A network outage won't prevent people from buying the PS4. And this time it comes after the peak shopping season, too."
Sony shares fell less than 1 percent to 2,5551 yen at the close in Tokyo, compared with a 0.4 percent advance in Japan's benchmark Topix index.