The concept of “packing” or “crypting” a malicious program is widely popular among threat actors looking to bypass or defeat analysis by static and dynamic analysis tools. Evasion of classification and detection is an arms race in which new techniques are traded and used in the wild. 

https://www.fireeye.com/blog/threat-research/2018/09/increased-use-of-delphi-packer-to-evade-malware-classification.html