Dunkin' says its own systems were not compromised. The company was tipped off to the potential breach by one of its security vendors on Oct. 31. Hackers targeted other companies, not Dunkin'. But they used the usernames and passwords they obtained to try to break into various online accounts across the Internet. Dunkin' security stopped most of these attempts, but customers who used their DD Perks username and password for accounts unrelated to Dunkin’ were vulnerable; hackers might have been able to log into some of these accounts.