[RCSession](https://attack.mitre.org/software/S0662) is a backdoor written in C++ that has been in use since at least 2018 by [Mustang Panda](https://attack.mitre.org/groups/G0129) and by [Threat Group-3390](https://attack.mitre.org/groups/G0027) (Type II Backdoor).(Citation: Secureworks BRONZE PRESIDENT December 2019)(Citation: Trend Micro Iron Tiger April 2021)(Citation: Trend Micro DRBControl February 2020)