No

A cyber attack is a cyber operation, whether offensive or defensive, that is reasonably expected to cause injury or death to persons or damage or destruction to objects.

Michael Schmitt et al; Tallinn Manual 1.0, pp 92
  • Cyber Operation?
  • Expected to cause death or injury to people or objects?
North Korean Disruptive Activity Against Sony Pictures does not match this definition. Here's a list of actual cyberattacks and and why this matters.

What happened?

Sony Pictures Entertainment is hacked with the malware deleting data and the hackers posting online employees’ personal information and unreleased films. An FBI investigation revealed North Korea to be behind the attack.