In 2012, the cloud-based storage company Dropbox was hacked, resulting in a compromise of 68 million user emails. What the company didn't realize at the time, though, was that user passwords were also stolen, the Guardian reports.
Recognizing the scope of the password hack, last week Dropbox reset an unknown number of user passwords and released a note to users indicating they should take preventative measures to change their passwords and that they "don’t believe that any accounts have been improperly accessed." The original data hack was a result of a Dropbox employee using the same password for his LinkedIn account as for his Dropbox account. (The first major LinkedIn hack was also in 2012.)
If you haven't changed your Dropbox password since 2012, you should do so right away—make sure it's a password you don't already use on another site. If you want to check if your email or password has been released on the Internet as a result of the hack, search for your email on the site Have I Been Pwned.