The University of New Hampshire has released a tool for gauging the level of threat any would-be attacker poses to the energy, emergency response or other sectors of critical U.S. infrastructure that rely heavily on IT.

The UNH Cyber Threat Calculator was shown at the Department of Defense Cyber Crime Conference in St. Louis in January. The calculator spits out results after weighing a threat's intent, technological capabilities and economic resources.

"There are increased risks as computer networks become more integrated with all aspects of our lives and infrastructure," said Andrew Macpherson, director of the technical analysis group at UNH Justiceworks and research assistant professor of justice studies at UNH, in a statement.

"Using cyber attacks to take some type of infrastructure, military, or civilian out of commission is, over the long run, problematic."

China and Russia are seen as being the two biggest threats to cybersecurity in the United States, he said, but it's not clear whether it is in their "best interest to use cyber attacks for strategic attacks."

Macpherson said it's possible an attacker might try to quietly do damage over time rather than making a digital Pearl Harbor attack.

"With approximately 85 percent of the cyber infrastructure owned by the private sector, it's not just a government problem," Macpherson said in a statement. UNH expects to make the calculator available to private industry security experts later this year.