AUSTIN, Texas - Concerns of voter fraud and election hacking are top of mind for some Texas lawmakers.

"(It was) an attempt to find vulnerabilities," said Keith Ingram, Texas Elections Division Director within the Texas Secretary of State's Office. "It's trying to raise the windows. It's rattling the doorknobs, seeing if they can find a way in. They did not find a way in in Texas."

During a hearing of the Senate Select Committee on Election Security Thursday, state election officials told members that foreign agents tried to hack into election databases in 2016 but were unsuccessful.

By and large, they said state's ballot machines are hack-proof since they are air gapped - meaning the machines don't connect to the internet. However, Rice University professor Dan Wallach said some are not as secure.

"If you are behind a firewall, that means you are on the internet," he said.

Wallach is the Computer Security Lab Manager at Rice University. He is also partnering with Travis County to create its next voting system, dubbed STAR Vote. He said it uses a mix of computer technology and a paper backup.

"The user experience looks a lot like getting a boarding pass at the airport," Wallach said. "You indicate what you want, and when you are done you get a printed ballot."

Voters would then insert that ballot into a secure ballot counting machine, which would immediately tally the votes through a double blind encryption process.

Federal funding helped counties purchase their current election systems around 2002. However, that funding had a time limit to use, so most of the country's voting systems are all about the same age and beginning to wear out, Ingram said.

Some lawmakers said at the committee hearing Thursday that voter registration is still not fraud-proof in their eyes. Voters must sign a statement swearing they are U.S. citizens and legally allowed to vote.

Jonathan White with the Texas Attorney General's Office said he prosecuted a woman in North Texas for submitting the form while after being denied the ability to vote because of her citizenship status. White did not provide any estimates as to how many people may be illegally on the voter rolls.