ThunderShell is a C# RAT that communicates via HTTP requests. All the network traffic is encrypted using a second layer of RC4 to avoid SSL interception and defeat network detection on the target system. RC4 is a weak cipher and is employed here to help obfuscate the traffic. HTTPS options should be used to provide integrity and strong encryption.
For any information related on how to use the tool and it's supported features check out the wiki
Current release is 3.1.1
RingZer0 Team 2017