Verkkounitedhealth has blamed its hack on a notorious criminal group called alphv, or blackcat, that the justice department says has been. Verkkothe wall street journal reported monday that the criminal hacking affiliate of alphv broke into change healthcare’s network using stolen credentials. Verkkounitedhealth says files with personal information that could cover a “substantial portion of people in america” may have been taken in the cyberattack. Verkkochange healthcare provides technology used to submit and process insurance claims — and handles about 14 billion transactions a year. Verkkoa cyberattack earlier this year against a unitedhealth group subsidiary has proved costly for one of the nation's largest employers.