The FBI disclosed a possible cyber security incident Saturday involving its own email domain after thousands of fake warning emails were sent across the globe.
The bureau said it was jointly investigating the incident with the U.S. Cybersecurity and Infrastructure Security Agency (CISA).
“The FBI and CISA are aware of the incident this morning involving fake emails from an @ic.fbi.gov email account. This is an ongoing situation, and we are not able to provide any additional information at this time,” the bureau said.
“The impacted hardware was taken offline quickly upon discovery of the issue. We continue to encourage the public to be cautious of unknown senders and urge you to report suspicious activity to ic3.gov or cisa.gov,” it added.
The European nonprofit Spamhaus Project said more than 100,000 inboxes were hit with the emails that could pose a "sophisticated chain attack.”
“These fake warning emails are… causing a lot of disruption because the headers are real, they really are coming from FBI infrastructure,” Spamhaus tweeted.