Sony said its PlayStation Network is up and running again after it was taken down Sunday by an apparent hacker attack.
The company said on the PlayStation Blog that the gaming network was shut down by a distributed denial of service (DDoS) attack, a common hacker technique that overwhelms a system with traffic and makes regular service temporarily unavailable. The company said it found no evidence of any intrusion to the network or of unauthorized access to users' personal information.
"Update: PlayStation Network and Sony Entertainment Network are back online, thanks for your patience and support," the official PlayStation Twitter account posted early Monday.
Sony decided to postpone maintenance work following the incident. "In light of [the] issue, the networks will not undergo the regularly scheduled maintenance, which was planned for Monday, August 25," Sony said on its blog. "We will provide an update shortly for when the maintenance will be rescheduled."
The attack, which followed a much more severe targeting of the gaming network in 2011, illustrated that the online service could still be vulnerable to being shut down by hackers.
The group claiming responsibility for the attack, the Lizard Squad, also claimed on Twitter on Sunday that there were explosives on an American Airlines plane carrying John Smedley, president of Sony Online Entertainment.
American Airlines spokesman Casey Norton said Flight 362 from Dallas/Fort Worth to San Diego, which was referenced in Lizard Squad's message, was diverted to Phoenix for a security-related issue, but he declined to provide further details. After the flight, which held 179 passengers and six crew members, was checked, it was allowed to continue to its destination and landed safely in San Diego.
Norton said American Airlines doesn't confirm any passenger names on its flights. However, a Twitter account claiming to belong to Smedley said his flight was diverted. Norton referred any additional questions to the Federal Bureau of Investigation, which he said is investigating the security issue.
In 2011, several Sony servers were attacked, leading to the exposure of the personal data of more than 100 million customers who signed up for PlayStation Network, Qriocity, and Sony Online. The company took the networks -- for downloading and playing games, movies, and music -- offline for about a month before slowly bringing them back up.
Updated at 7:35 a.m. PT: Adds comments from an American Airlines spokesman.