Since North Korea isn't getting the attention they want by threatening to sink Hawaii (although they seem to be doing a good job in Tuvalu) they decided on another form of attack - cyber. The Koreans used a DDoS attack to take down websites, such as South Korea's national assembly, defense ministry and Shinhan bank. They also attempted to take down the New York Stock Exchange and White House, but were deflected by US Internet-defense forces.
John Bumgarner from the US Cyber Consequences Unit said,
There's been a lot chatter recently about cyber-war. The North Koreans may have felt they were not getting enough attention launching missiles so they moved into another potential warfare – cyber. It's a form of sabre rattling. But the big question is, did the North Koreans launch it themselves or did someone do it for them?
Either way, this is an interesting situation - a government-sponsored cyber attack wasn't as effective as a 4chan-sponsored cyber attack. For shame.