Bitcoin Talk Breach

In May 2015, BitcoinTalk-the world’s largest Bitcoin discussion forum-suffered a major data breach that compromised approximately 501,407 user accounts. Attackers exploited a social engineering attack against BitcoinTalk’s ISP, NFOrce, to gain short-term access to the forum's database. During the brief window of intrusion, the attackers managed to extract a substantial amount of sensitive information, including usernames, email addresses, passwords, dates of birth, genders, website activity data, as well as security questions and answers. While a minority of the compromised passwords were stored using MD5 hashing with unique salts, the majority were secured with a more robust sha256crypt method, which made immediate mass cracking difficult.