The Federal Bureau of Investigation is acknowledging that hackers compromised its email servers on Saturday and sent spam messages.
The fake emails appeared to be from a legitimate FBI email address ending in @ic.fbi.gov, the FBI said in a statement. The agency described it as an “ongoing situation.” The hardware impacted by the incident “was taken offline quickly upon discovery of the issue,” the FBI said.
The spam emails went to 100,000 people, according to NBC News, and warned recipients of a cyberattack on their systems. The FBI and Department of Homeland Security routinely send legitimate emails to companies warning them about cyber threats. This is the first known instance of hackers using that same system to send spam messages to a large group of people, NBC reports.
The Spamhaus Project, a threat-tracking organization, posted on Twitter what it said was a copy of one such email. It showed a subject line of “Urgent: Threat actor in systems” and appeared to end with a sign-off from the Department of Homeland Security.
Both the FBI and the Department of Homeland Security’s Cybersecurity and Infrastructure Security Agency are aware of the incident, the FBI statement said.