Dropbox, Evernote, Google Drive, Apple iCloud. Chances are if your employees have Internet-connected mobile devices, they are using these and other services to store and transmit your company data — with or without your approval. That’s according to a new study from Enterprise Strategy Group, which found that while more than 75 percent of companies it surveyed had policies that prohibit the use of online file sharing and related tools, by and large their employees went ahead and used them anyway.