Sony's online PlayStation store was inaccessible to users for a short time on the 8th of December in the latest possible cyberattack on the electronics and entertainment company.
Sony Computer Entertainment in Tokyo said the problem lasted two hours before it was fixed globally. It said the cause is under investigation, but there is no sign of any material being stolen.
The previous week, the computer systems of Sony Pictures Entertainment were disrupted by a cyberattack and confidential information including unreleased movies was leaked on the Internet.
North Korea was among the suspects, but it has denied responsibility.
The FBI is investigating threatening emails sent to some employees of Sony Pictures Entertainment, and is trying to identify the person or group responsible.
There was no indication of a link between the PlayStation and Sony Pictures incidents.
A hacker group calling itself Lizard Squad appeared to take responsibility for the attack on its Twitter account, tweeting "PSN Login #offline."
Earlier this year, Lizard Squad warned that explosives might be on a flight that included a Sony executive among its passengers, and claimed responsibility for a disruption to the PlayStation network. American Airlines diverted the domestic US flight to a nearby airport.
In that incident, hackers orchestrated a so-called denial-of-service attack against Sony, which involved overwhelming the company's game network with fake visits so that legitimate users couldn't get through.
In 2011, hackers compromised the company's network including the personal data of 77 million user accounts. Since then, the company has repeatedly said its computer security has been upgraded.
A Denial-Of-Service attack (DDoS) attack is Form of electronic attack involving multiple computers, which send repeated HTTP requests or pings to a server to load it down and render it inaccessible for a period of time.
Protection from these attacks is difficult because, as one expert put it: "DDoS is...simple, cheap, unsophisticated, and effective."
Because of this simplicity, attacks could come from anywhere at anytime. If attacked, "folks that don't take active measures to ensure the resilience of their networks are going to get knocked over," said another expert. "They need to do everything they can to increase resiliency and availability." Accordingly, he recommends implementing "all of the industry best and current practices for their network infrastructure, as well as applications, critical supporting services, including DNS."
