Sony has pointed the finger of blame for last month's PlayStation Network security breach at the Anonymous hacking collective.
Sony Computer Entertainment boss Kaz Hirai made the revelation in an open letter addressed to a US House of Representatives subcommittee answering questions raised in a recent inquiry into the incident.
"We discovered that the intruders had planted a file on one of our Sony Online Entertainment servers named 'Anonymous' with the words 'We are Legion'," summarised Sony communications chief Patrick Seybold on the PlayStation Blog.
Anonymous, who had launched a series of cyber-attacks on Sony's operations earlier this year following the Geohotz court case, has denied any involvement.
"Anonymous is not attacking the PSN at this time," insisted an Anonymous spokesperson last month.
"We realise that targeting the PSN is not a good idea. We have therefore temporarily suspended our action, until a method is found that will not severely impact Sony customers."
Hirai's letter also reconfirmed that no fraudulent credit card use has been reported following the hack.
"As of today, the major credit card companies have not reported any fraudulent transactions that they believe are the direct result of this cyber attack."
There's still no confirmation of exactly when PlayStation Network will be back online.
"We are working around the clock to have some PlayStation Network services restored and we'll be providing specific details shortly," explained Seybold.