In the waning days of his campaign to win the White House, Donald Trump has been warning his supporters that the presidential vote is being "rigged" against the Republicans and in favor of rival Hillary Clinton, a Democrat.

"The whole thing is one big fix!" an energetic Trump told a cheering crowd recently at a North Carolina campaign rally. "One big ugly lie; it's one big fix!"

Trump campaign officials have been quick to clarify that when Trump talks about "rigging," he's usually referring to what he sees as media bias against his candidacy. But all the talk of election irregularities has elevated concerns among some Americans about the security of their votes — and perhaps in one regard, with good reason.

For several months, cybersecurity analysts have been sounding alarm bells about the U.S. election system, calling it porous and "painfully vulnerable" to cyberattacks. Worse, just days before Tuesday's vote, some analysts warned that hackers of even moderate talent could possibly throw the results of the 2016 presidential election into chaos.

Voters cast ballots at the Santa Clara County Regi Voters cast ballots at the Santa Clara County Registrar of Voters in San Jose, Calif., Oct. 24, 2016. Voters cast ballots at the Santa Clara County Registrar of Voters in San Jose, Calif., Oct. 24, 2016.

Security is expensive

Elections in the U.S. are run individually by the 50 states plus the District of Columbia. Secretaries of state, both Republicans and Democrats, insist their systems are secure.

That message was recently echoed by Thomas Hicks, chair of the U.S. Election Assistance Commission, who told members of the U.S. House of Representatives, "There's no national system that a hacker or a bad actor can infiltrate to affect the American elections as a whole."

Hicks' views are not shared among many cyber researchers.

"I'm pretty worried," said J. Alex Halderman, director of the Center for Computer Security and Society at the University of Michigan. "We're facing some pretty serious threats when it comes to security and elections. I'm quite worried that in an election soon we'll see real attacks that will either try to disrupt the election or possibly would try to change votes."

Halderman told VOA the rise of sophisticated nation-state actors over the past decade or so has outstripped the capabilities of many civil servants at the state and local level who are directly responsible for running elections.

"Elections aren't that sexy," Halderman said. "We don't like to fund tech for elections. It seems like a luxury to have new voting equipment. We need equipment that's secure, systems that can withstand attacks by other nations. [But] it won't come for free."

Halderman hopes all the attention on voting-system vulnerabilities will motivate state governments to invest in cybersecurity for the 2020 elections. But he said it's already too late to bolster security for this year's elections, and that could cause skepticism about the results.

"I just hope this election isn't close," he said.

FILE - Voters cast ballots in the Illinois primary FILE - Voters cast ballots in the Illinois primary in Hinsdale, Ill., March 18, 2014. Illinois' top election officials insist that a recent hack into state voter rolls, which contain the names of 8 million active voters, does not pose a threat to the Nov. 8 election. FILE - Voters cast ballots in the Illinois primary in Hinsdale, Ill., March 18, 2014. Illinois' top election officials insist that a recent hack into state voter rolls, which contain the names of 8 million active voters, does not pose a threat to the Nov. 8 election.

Swinging elections 'a cakewalk'

The idea that state elections systems are vulnerable to hackers is not exactly news. Earlier this summer, the FBI began an investigation into breaches of elections systems in Illinois and Arizona, while an unnamed Department of Homeland Security official recently told Politico that hackers had "intensely probed" state elections systems in 20 states. Law enforcement officials have pointed the finger at Russian state-supported hackers for the attacks, a claim the Kremlin denies.

Election officials like Washington Secretary of State Kim Wyman say their systems are secure because they're "air-gapped," or unconnected to the internet.

"We have full and complete confidence in the integrity of our system," Wyman told the Chinook Observer. "Every vote will be tabulated as the voter intended."

Yet James Scott is unpersuaded. "If these guys are saying, in their official capacity, that an air-gapped defense is sufficient, they're truly unqualified to have their jobs," Scott told VOA.

"Time and time again, we've seen that air-gapped systems don't work; they're not a defense anymore," he said. "Stuxnet, Uroburos, AirHopper, BitWhisper, ProjectSauron — these are all instances where hackers easily got past air-gapped protection."

Scott is a senior fellow at the Institute for Critical Infrastructure Technology, or ICIT, which advises private and public organizations on infrastructure cybersecurity. He and an ICIT colleague recently published a report examining voting security titled "The Painfully Vulnerable Election System and Rampant Security Theater." He said the report's title says it all.

"We set out to demonstrate that the systems were indeed secure," Scott told VOA. "We thought there's no way these systems are that vulnerable. After a week, we were just blown away; swinging elections at the local level is a cakewalk."

A sign displays absentee voting hours in Marietta, A sign displays absentee voting hours in Marietta, Ga., as a Cobb County sheriff's deputy sits in his vehicle, Oct. 17, 2016. Facing unprecedented warnings of a "rigged" election from Donald Trump, state officials around the country are rushing to reassure the public.r A sign displays absentee voting hours in Marietta, Ga., as a Cobb County sheriff's deputy sits in his vehicle, Oct. 17, 2016. Facing unprecedented warnings of a "rigged" election from Donald Trump, state officials around the country are rushing to reassure the public.r

Code-poisoning

The report details at least 20 different vulnerabilities that could provide hackers entry into state voting systems, with the authors noting that none of the threats they discuss could be considered new or novel to even amateur hackers.

Scott said sophisticated groups known as advanced persistent threats (APTs) should be expected to employ great stealth. "The Russian adversary is the most stealthy and sophisticated that we have," he said, adding that with the right techniques, hackers could even affect the presidential election.

One such tactic already employed in commercial attacks by Russian hackers is code-poisoning. Imagine, said Scott, hackers inject malware into a voting system manufacturer's code. Additionally, the malware is geotagged to only target certain voting systems in certain counties across the nation.

When the machines are updated, the malware silently passes to each electronic tabulator. The malware switches on when the machines are powered up on Election Day. It invisibly alters the votes and then automatically self-erases once tabulation is complete.

"People think you have to infect all the machines used across the country, which just isn't the case," said Scott. "You've got die-hard red and blue states, and then you have swing states. And within the swing states you have swing counties.

"Focus on those few swing regions, add to it the stealth and sophistication of a dedicated APT, and it becomes very possible to throw a national election. It's doable and realistic, and that's really too bad," he said.

VOA's Steve Baragona contributed to this report.