Hackers group that identifies itself as #GOP (Guardians of Peace) claimed responsibility for the hack and apparently stolen reams of internal corporate data as well. Sony believes that the cyber attack on its network is the payback for upcoming Kim Jong assassination comedy film “The Interview” Sony Pictures is working with the Federal Bureau of Investigation (FBI) to investigate the whole matter. FBI investigating the matter said that cyber criminals have used malicious software to launch destructive cyber-attacks including the one occurred at Sony Pictures Entertainment.
Source: https://thehackernews.com/2014/12/Sony-Hack-Cyber-Attack.html