Trojans are malicious applications that pose themselves as legitimate software in order to trick users to install them. Once on the victim's machine, it may run any number of malicious process to steal vital information or inflict damage to other software.
Sandesa is a downloader trojan that downloads and executes more malwares once it is executed.
This trojan drops a file named "system.dll" into "SystemDrive"( usually c:\)and executes it. This file contains further instructions to download additional files.