Hackers backing Iran have targeted U.S. banks, defense contractors and oil industry companies following American strikes on Iranian nuclear facilities.

Microsoft says the early June disruptions to its Microsoft’s flagship office suite — including the Outlook email apps — were denial-of-service attacks by a shadowy new hacktivist group.

A ransomware attack has paralyzed the networks of at least 200 U.S. companies.

The threat apparently came from the same cyberespionage campaign that has afflicted FireEye, foreign governments and major corporations, and the FBI was investigating. FireEye’s customers include federal, state and local governments and top global corporations. Cybersecurity experts said last week that they considered Russian state hackers to be the main suspect in the FireEye hack. Federal government agencies have long been attractive targets for foreign hackers. “I suspect that there’s a number of other (federal) agencies we’re going to hear from this week that have also been hit,” Williams added.

The U.S. believes North Korea and Russia capitalized on the stolen tools to unleash devastating global cyberattacks. The nation’s Cybersecurity and Infrastructure Security Agency warned that “unauthorized third-party users” could similarly abuse FireEye’s stolen red-team tools. FireEye has been at the forefront of investigating state-backed hacking groups, including Russian groups trying to break into state and local governments in the U.S. that administer elections. Its threat hunters also have helped social media companies including Facebook identify malicious actors. FireEye said it is investigating the attack in coordination with the FBI and partners including Microsoft, which has its own cybersecurity team.

LONDON A Florida teen was identified Friday as the mastermind of a scheme earlier this month that commandeered Twitter accounts of prominent politicians, celebrities and technology moguls and scammed people around the globe out of more than $100,000 in Bitcoin. The hack alarmed security experts because of the grave potential of such an intrusion for creating geopolitical mayhem with disinformation. The court documents released Friday show how federal agents tracked down the hackers through Bitcoin transactions and by obtaining records of their online chats. Internal Revenue Service investigators in Washington, D.C., identified two of the defendants by analyzing Bitcoin transactions on the blockchain the universal ledger that records Bitcoin transactions that they had sought to make anonymous, federal prosecutors said. ___This story has been corrected to show that participants in the operation, not the hacker identified as Kirk, discussed it with The New York Times.