[GreyEnergy](https://attack.mitre.org/software/S0342) is a backdoor written in C and compiled in Visual Studio. [GreyEnergy](https://attack.mitre.org/software/S0342) shares similarities with the [BlackEnergy](https://attack.mitre.org/software/S0089) malware and is thought to be the successor of it.(Citation: ESET GreyEnergy Oct 2018)