Sony PlayStation and Microsoft Xbox networks were both disrupted yesterday, with disruptions continuing into today. LizardSquad claims they did it — no announced motive. See the Christian Science Monitor's Passcode for a profile of the group, and its baffling celebrity.
US attribution of the Sony Pictures hack to North Korea remains controversial, with insiders and hacker collectives providing the principal alternative suspects. Another alternative theory seems thin and circumstantial, but perhaps no more so than attribution of cyber attacks tends to be: language the "Guardians of Peace" used in their communications strikes some (at Taia Global, at any rate) as containing errors Russian native speakers characteristically make when attempting English. (Languages checked include Korean, Russian, Mandarin Chinese, and German. Taia Global had an admittedly small corpus of messages to work on.) But leading explanations still point to North Korea, even to one General Kim Yong-chol.
There is consensus, however, that better information-sharing and network security are the order of the day. Lawyers, defense intellectuals, and policy wonks debate the nature of cyber war (what constitutes, when justified, how to wage, etc.). See the New York Times for a series of connected op-eds.
The US, Japan, and South Korea announce closer intelligence cooperation against what they regard as a common threat from the DPRK. South Korea asks China for assistance with an investigation into attacks on networks of a nuclear power producer (the reactors themselves are reported safe and secure) as some believe China provides cyber training and tools to North Korea.