According to the company, “Our security teams are always watching out for new threats to our users. As part of these ongoing efforts, we learned about an old set of Dropbox user credentials (email addresses plus hashed and salted passwords) that we believe were obtained in 2012. Our analysis suggests that the credentials relate to an incident we disclosed around that time”.
It is also highly recommended that you change any other passwords for sites which shared the same password as your Dropbox account. Remember to use strong passwords, use a different password for each account, and utilize two-step verification, when possible. If you have any other questions or concerns, feel free to reach out to us at Optfinity anytime!