The FBI has issued a warning to American businesses, encouraging them to be on high alert for Iranian hacking groups targeting energy and defense firms as well as educational institutions.

A 'flash report', seen by Reuters, states offers some technical details of the hacking techniques used, along with advice about how best to prevent the damaging attacks.  It encourages any organizations that suspect they have been attacked to contact the FBI urgently.

The report seems to be an extension of the research done by security firm Cylance on 'Operation Cleaver', reported by We Live Security here, an attack for Iranian hacker groups targeting 50 companies in the United States, England, China, France, Germany, Canada, India, Israel, Mexico, Turkey, South Korea, Kuwait, Pakistan, Qatar, Saudi Arabia and the United Arab Emirates.

Computing speculates that methods of attack favored by the hackers could include "SQL injection, spear phishing, and water-holing, all of which have been used to extract confidential information from organizations across 16 countries."

"By exposing our intelligence on Cleaver, we hope the information we share can reveal the techniques and tools of this group, drawing global attention to attacks on critical infrastructure and preventing attacks which could endanger human lives," said Cylance's CEO, Stuart McClure.

The report highlighted that the majority of the attacks came from two Tehran based IP addresses, but offered no further speculation about the source beyond that, notes Engadget.

The FBI has offered no further comment on the release with Reuters stating that "an FBI official did not provide further details, but said the agency routinely provides private industry with advisories to help it fend off cyber threats."