Wired:

On Wednesday, at about 12:15 pm ET, 1.35 terabits per second of traffic hit the developer platform GitHub all at once. It was the most powerful distributed denial of service attack recorded to date—and it used an increasingly popular DDoS method, no botnet required.

GitHub briefly struggled with intermittent outages as a digital system assessed the situation. Within 10 minutes it had automatically called for help from its DDoS mitigation service, Akamai Prolexic. Prolexic took over as an intermediary, routing all the traffic coming into and out of GitHub, and sent the data through its scrubbing centers to weed out and block malicious packets. After eight minutes, attackers relented and the assault dropped off.

How the attack was pulled off:

Database caching systems [memcached servers] work to speed networks and websites, but they aren’t meant to be exposed on the public internet; anyone can query them, and they’ll likewise respond to anyone. About 100,000 memcached servers, mostly owned by businesses and other institutions, currently sit exposed online with no authentication protection, meaning an attacker can access them, and send them a special command packet that the server will respond to with a much larger reply.

Interesting story. Leaves me wondering why the attackers relented. Did a human plan it to be this long? Was there some mechanism that measured the impact of the attack, it stopped when Prolexic stepped in? Was the time limit to avoid being traced?