It is difficult to fathom that a threat actor may be able to breach the networks of a reputed security company. Yet, this is not only possible but also happened in the past; and it is not far-fetched to believe that it is the case with at least three antivirus makers, as reported by BleepingComputer earlier this week. […]

from https://www.bleepingcomputer.com/news/security/new-details-emerge-of-fxmsps-hacking-of-antivirus-companies/