Executives at Sony Pictures Entertainment turned to old-school security measures in a last-ditch attempt to keep corporate data private - digging out corporate BlackBerries found in a basement in California, Mashable reports.

Speaking to The Wall Street Journal, Michael Lynton, the CEO of Sony Entertainment switched to a ‘phone tree’ system where information was relayed person-to-person via mobile devices and private Gmail accounts rather than corporate ones.

Key to this was a stash of old, unused BlackBerry devices, according to the New York Times' report  - which were used, Mashable said, because emails sent via the devices travelled via BlackBerry’s servers rather than Sony’s.

Old-school security

Staff also communicated via text message over the course of weeks in which the extent of the attack became clear - and the company rapidly adapted to working without voice mail, corporate email or digital production systems.

Technical staff debated whether to take the company entirely offline.

The extent of the attack was entirely unknown in the days afterwards: the company’s first press release simply stated that the company faced ‘IT issues.’

Staff debated taking the company offline

Lynton told the New York Times he anticipates it will take five to seven weeks for the company’s working practices to return to normal, as systems from email to payroll have all migrated to temporary, jury-rigged new versions.

Lynton said, ‘“It took me 24 or 36 hours to fully understand this was not something we were going to be able to recover from in the next week or two.’