ATF declares ‘major incident’ as ransomware gang claims hack

The ATF has declared a cyberattack on a stand-alone system a "major incident" after the system—separate from the bureau's network—was breached; the system reportedly contained information such as targets of ATF investigations. The Qilin ransomware gang claimed responsibility on its leak site but did not provide evidence of leaked data; the classification as a major incident obliges disclosure to Congress and follows other recent federal agency breaches.