Ask HN: What's the post mortem of the big Quora hack?

At the time, Quora published a blog post saying they're "sorry for any concern or inconvenience" and that they're still investigating the precise causes: https://blog.quora.com/Quora-Security-Update

But then they didn't follow up with their conclusions:

1. Who hacked 2. How the hack was executed 3. What are the steps they took to help affected users (if at all) 4. What are the steps they took to prevent future hacks from happening in the future (if at all)

Does anyone know?