A second APT, possibly linked to the Chinese government, could be behind the Supernova malware. The group used a separate vulnerability from the Sunburst backdoor that was at the heart of the sprawling espionage campaign that came to light in December. Microsoft concluded in December that a second group of malicious actors may have exploited a SolarWinds bug to install Supernova. The malware was originally discovered in December, and Microsoft noted at the time that because the malware didn t match the fingerprints of the malware, Supernova may have originated from another APT group. The USDA payroll system, called the National Finance Center (NFA) was targeted.
Source: https://threatpost.com/second-solarwinds-attack-group-usda-payroll/163635/