Sony Computer Entertainment chief Kaz Hirai has issued a lengthy 8-page response to concerns raised by the U.S. Congress earlier last week over the recent PSN security breach, which has left a total of 101 million accounts compromised. In the letter, Hirai sheds light on particulars of Sony’s findings, including a file planted by the attackers that read ‘We are Legion,’ an Anonymous tagline.

“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,” noted Hirai.

Hirai also stressed that the attack on Sony Online Entertainment’s operation was not a second intrusion, it occured around the same time as the PSN breach. The intruders were able to gain access by exploiting a “shared infrastructure” across servers.

Of course, the mere existence of a file implicating Anonymous doesn’t necessarily mean that those involved in the DDOS racket also played a hand in hacking PSN. Most likely, the incidents are completely unrelated, but it’s being considered as a possible link.

Additionally, another interesting nugget from the letter is that Sony’s network staff discovered that off-scheduled system reboots on April 19, a day before the breach was identified.

For those that’d like to check out the letter in full, head on over to Sony’s Flickr account.

Thanks, PS Blog.

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