(CNN/Money) U.S. law enforcement officials revealed the hack attempts on Wednesday at a conference of American energy firms who were meeting about national security concerns.
"ISIL is beginning to perpetrate cyberattacks," Caitlin Durkovich, assistant secretary for infrastructure protection at the Department of Homeland Security, told company executives.
Investigators would not reveal any details to CNNMoney -- or cite evidence of specific incidents.
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But they did say the attacks by the Islamic State have been unsuccessful. Terrorists are not currently using the most sophisticated hacking tools to break into computer systems and turn off or blow up machines.
"Strong intent. Thankfully, low capability," said John Riggi, a section chief at the FBI's cyber division. "But the concern is that they'll buy that capability."