Administrators of the Ethereum Project said the platform to trade the Ethereum crypto-currency incurred a breach affecting more than 16,500 users.
The attacker used social engineering to gain access to a mobile phone number which allowed them to gain access to other accounts and ultimately compromise usernames, email addresses, profile data, public and private messages, and hashed passwords, according to a 19 December security blog post.
Administrators said the information stolen may be enough for an attacker to cherry-pick the importance of individuals using the platform or identify individuals with large account balances.
The breach took place on 16 December although the compromised database was reportedly a backup from April 2016. A hacker purporting to be the same individual that stole more than US$300,000 from Chinese Investor Bo Shen earlier this month, reached out to the administrators and claimed responsibility for the attack.