PlayStation boss Kaz Hirai has admitted that Sony "may never know" exactly what data hackers stole during the PSN security breach in April.
Speaking to BBC Click, Hirai said the company knew "information was accessed" for up to 100m accounts, but could not be certain "what part... [was] actually taken from our servers."
He added: "The people that intruded our systems are very good in hiding their tracks as they left our systems, so we might not know for a very long time or we may never know."
Hirai also revealed that Sony did not know if "any credit card information was taken", explaining that the company "shared that as a potential possibility" in the interests of consumer safety.
Despite the media focus on Sony, he insisted: "It's certainly not just a Sony issue, but more of a corporate issue for everybody. As you probably know, even in this past week or so there have been other organisations and companies where a similar sort of intrusion has occurred."
Asked what Sony had learned from the experience, he replied: "Whether we're talking about a large corporation like Sony as well as smaller organisations, whoever deals with personal information as well as credit card information needs to be very vigilant about how that data is being secured."