The information compromised in the attack include name, email address, encrypted password, data imported from linked networks, public content and actions like questions, comments, answers, upvotes and non-public content.
Non-public content and actions, e.g. answer requests, downvotes, direct message.
It's worth noting that if you've used and answered questions anonymously in the past, your data is safe as Quora doesn't store the identities of such users. In June 2016, hacking group OurMine broke into Google CEO Sundar Pichai's Quora account.
Quora says the latest data breach is unlikely to result in identity theft as it does not collect sensitive private information of users.
"We are working rapidly to investigate the situation further and take the appropriate steps to prevent such incidents in the future", Quora CEO Adam D'Angelo said in the post, adding that it's now in the process of notifying users whose data has been affected. The company has also notified law enforcement agencies regarding the same and "retained a leading digital forensics and security firm".
Quora has posted an extensive FAQ explaining details of the data breach, but the FAQ doesn't mentioned how user passwords were hashed, i.e. run through a one-way encryption algorithm.
Quora added that the overwhelming majority of content accessed was already public on its site. Users who chose the same password to protect accounts on a different service should immediately reset those passwords as well.
If you want to simply delete your Quora account, visit your account privacy settings and choose "Delete Account".
Users who authenticated on Quora with passwords will have these invalidated as well, d'Angelo said.
"We are working rapidly to investigate the situation further and take the appropriate steps to prevent such incidents in the future".