Sony said that it's called in three computer security and forensics firms to help investigate the data breaches that compromised the user account information of more than 100 million of its customers. The firms named by Sony are Data Forte, Guidance Software, and Protiviti.

Sony brought in some of those digital forensic investigators--and also notified the FBI about the breach--on April 22, the day after its network engineers first suspected that its systems had been breached. As the scale of the breach became apparent, growing to include not only the PlayStation Network and Qriocity service, but also the Sony Online Entertainment games service, Sony began calling in the other forensics companies.

But government officials--and not a few customers--have been critical about what they see as Sony's slow response to resolving the breach and restoring services, and political pressure is mounting. According to Bloomberg News, Sony has been subpoenaed by New York attorney general Eric Schneiderman, who is "seeking information on what Sony told customers about the security of their networks, as part of a consumer protection inquiry."

So, what exactly are Sony and its digital forensic investigators doing, and why haven't services been restored yet? "My guess right now is they're still trying, to a certain extent, to determine what happened," said Alex Cox, principal research analyst at NetWitness, which sells network-monitoring appliances. "When you talk intrusion analysis and breach analysis, it's a pretty specialized skill set and typically one that companies don't have internally. Because hopefully, it's infrequent enough that people don't need to have their own internal teams. But the fact that Sony is bringing in outside help tells me that they don't have the staffing."

As a result, the new teams will take time to come up to speed on the systems, to then deduce what happened. "Forensics work, you can look at it as a crime scene investigation from a computer security standpoint," he said in an interview. "You're looking for clues that get you from point to point, so you hopefully have a solid understanding of the how/what/where/when/why of the intrusion."

The scale of the compromised data may also slow analysis and recovery efforts, and Sony has said that at least 10 servers were compromised. "That certainly does complicate the forensic process, because you have to look at all these systems ... and you need to have a very solid understanding of how the technology works," said Cox. "A lot of times when this happens, you find out that the company that implemented this solution didn't have a 100% understanding of all the complexities of the system."

Poor preparedness may also have played a part in the Sony--as well as Epsilon--breaches, according to Eugene Spafford, a professor at Purdue University who's also the executive director of its Center For Education and Research in Information Assurance and Security (CERIAS). "Presumably, both companies are large enough that they could have afforded to spend an appropriate amount on security and privacy protections of their data; I have no information about what protections they had in place, although some news reports indicate that Sony was running software that was badly out of date, and had been warned about that risk," he said on Wednesday to a House Subcommittee on Commerce, Manufacturing, and Trade hearing into the Sony data breach.