Iranian authorities are sweeping up hundreds of people deemed suspected spies or infiltrators. Some worry the campaign could become a broader crackdown on political opponents and minorities.

"The volume of attacks appears to be relatively low," said Nicole Fishbein, a senior security researcher with the Israeli company Intezer. "The techniques used are not particularly sophisticated." Online vigilante groups alleged by security analysts to be acting at Iran’s direction boasted of hacking a series of Israeli and Western companies in the wake of the airstrikes.