Cybersecurity experts almost unanimously point to Russian military and intelligence community hackers as the source.
Democrats have been painting Trump as a friend of the Russian government, which has a tense working relationship with the U.S., for much of the campaign. She said the state has deployed the type of cybersecurity needed to fend off such threats.
U.S. officials have been on edge following a series of cyber attacks on federal targets, including the Internal Revenue Services (IRS) in 2015.
After taking the registration system offline, it was discovered that an official's username and password had been posted online. "Two state election boards have been popped, and data has been taken. We didn't find any evidence that anyone had penetrated the system", Roberts said.
When asked if our election system being tampered with was a possibility, the tech security guru agreed some of these fears are founded.
In that call, Johnson said that while DHS isn't aware of any particular cyber threat against election-related computers, it's "critically important" to make sure that election systems are secure amid a rapidly changing threat landscape, according to a DHS summary of the call. Voter registration databases may contain a significant amount of personal information that can be used in conjunction with other information that's already been taken from other compromised systems, or it may provide enough information on its own. No data was removed in that attack, the official said. "We are highly confident that no information was added, deleted or altered".
The elections board, however, warned that "due to the ambiguous nature of the attack, we may never know the exact number of affected voters".
"This is a wake-up call for other states to look at their systems", Tom Hicks, the chairman of the federal Election Assistance Commission, told Yahoo. As a result, Reagan shut down the state's voter registration system for almost a week. "It's incredibly important to expect more from our elections officials".
SEE MORE: Did Russians Hack The DNC? Bureau officials on Monday declined to comment.
Although the warning did not specify which states were targeted, Yahoo and local news reports identified IL and Arizona. The actions by the Federal Bureau of Investigation and related activity by the Department of Homeland Security were first reported by Yahoo News.
Information potentially at risk from voter databases could be used for ID theft.
IL was the victim of a voter database hack in July and was forced to shut down its systems for 10 days.
In Dauphin County, voting regulators say there won't be any problems with their ballot machines come Election Day.