North Korea? Cyber war? This is crap. People in North Korea starve! They have no cars, not even shampoo. They have no resources or man power to start anything "cyber".
So this could plausibly be one such strike in an on-going conflict that is far more 'real' than script kiddie squabbling.
Could have been a penetration attack to steal technological secrets.
Could have been a penetration to plant backdoors/loggers for later use.
Could be service disruptions to hamper a particular project. (Take down the network serving No Fly List sorts of updates to get a possibly-compromised agent on a plane or over a border.)
Could just be a 'recon' attack to see what we have connected and how we react. A sort of digital equivalent to the kinds of 'disruption' that we financed and supported from Okinawa toward China for many years.
But I personally find it hard to believe that any state-sponsored cyber 'strike' would be limited to a DDoS on public-facing services. That sounds like a smokescreen at best.
http://en.wikipedia.org/wiki/Economy_of_North_Korea
There might be a little extra in there some where for a trip to Fry's for some l33t hax0r t00lz.