" Dropbox users themselves may be the source of security problems. If you are sharing a folder with 100 users, a couple of them are bound to be using easily guessed passwords to guard their accounts (the names of pets or first-born children, 'password', etc.). Sharing links can also lead to problems, if the wrong link is shared or someone posts the link online or in some other public forum. "

― Ian Lamont , Dropbox in 30 Minutes: The Beginner’s Guide To Dropbox Backup, Syncing, And Sharing