Sunburst infamously used a compromised update mechanism to infect thousands of Solar Winds customers with a backdoor Trojan. This page is a great resource for your organization and contains the latest research and insights into Sunburst as well as protection recommendations for these types of advanced attacks.
Highlights include:
Explainer videos featuring Eric Chien, leader of the Attack Investigations Team
Blogs from Symantec Threat Hunter team with analysis and telemetry