The cyberattack on UnitedHealth Group's subsidiary Optum, initially suspected to be a nation state attack, is now reported to be the work of the ALPHV/BlackCat ransomware gang, a Russian-linked group.

Optum Solutions, a UnitedHealth Group company, manages the Change Healthcare platform. This platform provides payment and billing management software used by numerous healthcare facilities, making it one of the largest health technology firms in the USA.

The cyberattack caused an outage that affected 119 Change Healthcare and Optum services and platforms, including healthcare organisations, clinics, and pharmacies, and created issues nationwide with billing, claims processing, and issuing prescriptions. The restoration timeline remains uncertain.

UnitedHealth did not reply to calls for comment. ALPHV/Blackcat has yet to claim responsibility for the attack.