LastPass hacked, hashed/salted master passwords and password hints exposed

[Silver Knight]

LastPass officials warned Monday that attackers have compromised servers that run the company's password management service and made off with cryptographically protected passwords and other sensitive user data. It was the second breach notification regarding the service in the past four years.

In all, the unknown attackers obtained hashed user passwords, cryptographic salts, password reminders, and e-mail addresses, LastPass CEO Joe Siegrist wrote in a blog post. It emphasized that there was no evidence the attackers were able to open cryptographically locked user vaults where plain-text passwords are stored. That's because the master passwords that unlock those vaults were protected using an extremely slow hashing mechanism that requires large amounts of computing power to work.

"We are confident that our encryption measures are sufficient to protect the vast majority of users," Siegrist wrote. "LastPass strengthens the authentication hash with a random salt and 100,000 rounds of server-side PBKDF2-SHA256, in addition to the rounds performed client-side. This additional strengthening makes it difficult to attack the stolen hashes with any significant speed."

http://arstechnica.com/security/2015/06/hack-of-cloud-based-lastpass-exposes-encrypted-master-passwords/