Mastodawn

DOJ actually detected the SolarWinds hack in its network back in May 2020 and Microsoft, Mandiant, SolarWinds all looked at it at the time, but didn't grasp what they were seeing. Six months later Mandiant publicly exposed the campaign. @kimzetter back in WIRED! https://www.wired.com/story/solarwinds-hack-public-disclosure/

DOJ Detected SolarWinds Breach Months Before Public Disclosure

In May 2020, the US Department of Justice noticed Russian hackers in its network but did not realize the significance of what it had found for six months.

WIRED