Cybersecurity and Infrastructure and Security Agency: Firewall Rules could have prevented follow-on attacks after SolarWinds attack. Agency: Blocking Outgoing Connections From Orion Would Have Stopped Malware. CISA: CISA agrees that a firewall blocking all outgoing connections to the internet would have neutralized the malware. The U.S. government believes that Russian hackers, likely working at the SVR intelligence agency, waged the espionage attack against Solar winds, which led to attacks on nine federal agencies and 100 companies.”]
Source: https://www.cuinfosecurity.com/cisa-firewall-rules-could-have-blunted-solarwinds-malware-a-16919