In this contentious election year, foreign hackers have taken a keen interest in the U.S. electoral system. Perhaps most memorable was this summer’s high-profile assault on Democratic National Committee computers, which exposed a number of unsavory emails and forced DNC Chairwoman Debbie Wasserman Schultz to step down. But state voter registration databases have also become popular targets for hackers looking to disrupt confidence in this year’s elections; over two dozen states have seen some form of cyberattack on their election systems this year. An apparent hacking attempt in June 2016 caused Arizona’s voter registration system to shut down for almost a week while state and federal officials investigated the source of the hack. The FBI later attributed the breach to Russian hackers.

Speaking at the Cambridge Cyber Summit this month, Arizona Secretary of State Michele Reagan revealed that the malware was traced to a highly sophisticated email designed to look like it came from an employee. Hackers used the email to obtain the username and password for a single election official, giving them access to Arizona’s entire voter registration database, which houses the personal information of more than four million Arizona residents. According to Secretary Reagan, election officials have taken several steps to protect Arizona’s election system from additional cyberattacks, including requiring employees to implement new and stronger passwords and multifactor authentication. Although Secretary Reagan has been adamant that hackers did not gain access to any mechanism for tallying votes, the mere possibility that election results could be compromised may be enough to cast doubt on this election, which some (including one major party candidate) have already alleged is “rigged.” This latest revelation from Arizona officials serves as yet another example of the importance of creating a culture of data security in the workplace and training employee–in all industries–to recognize the signs of fraudulent emails.

See Secretary of State Reagan’s complete interview here.