US Cyber Command is said to have conducted offensive operations against Iranian targets as a reprisal for Tehran's attacks on commercial shipping in the Gulf of Oman, and for the shootdown of a US Global Hawk unmanned drone. Yahoo, which broke the story late Friday, said the attacks were directed against an Iranian intelligence unit responsible for supporting attacks against shipping by tracking tanker traffic. The specific Iranian agency was unnamed, but it's said to be associated with the Revolutionary Guard. The Washington Post reported that Cyber Command had disabled Iranian rocket and missile command and control systems in the region, which (if so) would be a direct riposte to the Global Hawk shootdown.
Reports of this US cyberattack are sourced to anonymous US officials not authorized to speak publicly. US Cyber Command has declined to comment for reasons of operational security. US Vice President Pence also declined comment, according to the Wall Street Journal, citing policy regarding comment on "covert operations." The Jerusalem Post reports that Iran says the US cyberattack indeed happened, but that it failed.
The US Cybersecurity and Infrastructure Security Agency (CISA) has also warned that Iran is increasing the tempo of cyberattacks against US targets. CISA cautions that Iran could be expected to engage in wiper attacks. These gain access to target networks through familiar methods, particularly phishing, password spraying, and credential stuffing, but their aim is data destruction, not theft. CISA's advice for staying safe from these and other threats may be found here.