An American lawsuit filed this week alleges that Sony laid off a number of staff in charge of maintaining the security of its online networks.
It also claims that the company invested more in securing its corporate information than it did in protecting the details of its customers.
Reuters reports that the suit also claims that Sony was aware of its security shortcomings prior to the PSN breach as it had already suffered a number of small lapses.
It says that "a substantial percentage" of its Sony Online Entertainment workforce were sacked in the period before the controversy, a number of whom were responsible for its online security.
Measures such as firewalls and other unspecified protections were installed on servers containing corporate information but not on those housing its customers details, it adds.