The Dropbox hack of 68 million user accounts is all over the news. A number of security researches have verified that the usernames and passwords are easily accessible to hackers. This attack occurred sometime around 2012. If you use Dropbox, here is what to do:
1) Determine if you're account has been hacked. The website below maintains a database of many different hacks that you can quickly search with your email address.
2) Reset your password. This is most important if you, like most people, reuse passwords between sites. You need to reset your Dropbox password and any others that use that same password.
Also, stop doing this! Get a password manager and use unique, random passwords for each login. Here a few good ones:
3) Enable dual factor authentication. This is highly recommended for EVERY login, but not every site supports dual factor. Your bank does and you must use it. Dropbox does. Here is how to enable it in less than 5 minutes.