Sony appears to have shifted the blame back to the hacktivist group Anonymous. Anonymous was allegedly conducting DDoS attacks against Sony around the same time as the PSN shutdown. Anonymous has responded to the indirect accusation by insisting that it is not responsible for the attack. Sony found a file labeled “Anonymous” on one of its servers, according to a letter to Congress. The letter does not explicitly accuse Anonymous of hacking the PlayStation Network, but says Sony is working with law enforcement to identify the responsible parties.”]
Source: https://www.csoonline.com/article/2128375/sony-shifts-blame-back-to-anonymous-for-psn-attack.html