https://arstechnica.com/information-technology/2020/12/feds-warn-that-solarwinds-hackers-likely-used-other-ways-to-breach-networks/

The supply chain attack used to breach federal agencies and at least one private company poses a “grave risk” to the United States, in part because the attackers likely used means other than the SolarWinds backdoor to penetrate networks of interest, federal officials said on Thursday. One of those networks belongs to the National Nuclear Security Administration, which is responsible for the Los Alamos and Sandia labs, according to a report from Politico.

“This adversary has demonstrated an ability to exploit software supply chains and shown significant knowledge of Windows networks,” officials with the Cybersecurity Infrastructure and Security Agency wrote in an alert. “It is likely that the adversary has additional initial access vectors and tactics, techniques, and procedures (TTPs) that have not yet been discovered.” CISA, as the agency is abbreviated, is an arm of the Department of Homeland Security.