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According to a report from Bloomberg, sources close to the ongoing investigation say the attack was mounted from Amazon Web Service's cloud computing platform.
The hackers used fake personal information to set up an AWS account. They rented servers in the cloud to carry out the exploit; the related AWS account has already been deleted.
In a previous statement, Sony pointed to loosely organized hacktivist collective Anonymous as the perpetrators behind the hack, citing the calling-card phrase "We are Legion," which was found on Sony's servers.
Anonymous countered with an uncharacteristic outright denial, saying that the responsible parties acted alone.