If a highly-sophisticated and motivated adversary wants into your network, then they will find a way. Proactive protection and a defense-in-depth approach to cybersecurity are imperative, but we must never forget the mantra, “assume compromise.”
Pragmatically, this ideal is most often put into practice through authentication, authorization and network segmentation. However, detecting data exfiltration is one of many anomalies that can be identified when looking through the lens of assumed compromise.