SolarWinds (2020)

The SolarWinds breach inserted backdoor code into Orion software updates, infiltrating 18,000 organizations including U.S. Treasury and DHS. Attackers maintained undetected access for an average of 9 months—over 2.8 times longer than the typical 95-day dwell time for advanced persistent threats. This espionage-focused attack outranks the MOVEit breach in strategic sophistication, targeting government networks rather than widespread extortion. The breach’s supply chain vector exposed sensitive communications from 100+ federal agencies, with estimated response costs of $100 million for SolarWinds alone.