hacker attack at Sony's

The Justice Department has opened an investigation into the security breach at Sony Corp., in which two separate attacks over the last month shut down Sony's PlayStation network and an online-gaming unit.

The federal probe comes as Sony said Wednesday, that its network might have been breached while it was defending it self from denial-of-service attacks by Anonymous, a loosely connected group of Internet activists who have successfully brought down the websites of other big corporations and was retaliating against Sony for bringing a civil suit against a hacker in federal court in San Francisco.

Also Wednesday, Kaz Hirai, Sony's executive deputy president, wrote in a letter to the House Subcommittee on Commerce, Manufacturing and Trade that the company "has been the victim of a very carefully planned, very professional, highly sophisticated criminal cyber attack designed to steal personal and credit card information for illegal purposes."

The attack on Sony's PlayStation network and Qriocity music-streaming service compromised the personal information of 77 million customers accounts. On Sunday, the company suspended service for Sony Online Entertainment, best known for creating online multiplayer games such as Ever Quest and the Matrix Online, after an intrusion exposed personal data for about 24.6 million subscribers.

Sony apologized Saturday and announced several "welcome back" freebies for PlayStation customers, including 30 days of free access to Qriocity for affected customers as well as 30 days of access to the PlayStation Plus online game service. The company will also provide credit card protection services to relevant customers, Hirai said.

New York Atty. Gen. Eric Schneiderman on Wednesday subpoenaed three Sony divisions  Sony Computer Entertainment, Sony Network Entertainment and Sony Online Entertainment for documents regarding their security, CNBC reported

Consumers have filed at least two lawsuits in California against Sony and are seeking federal class-action status.