What is system

This process is a single thread running on each processor, which has the sole task of accounting for processor time when the system isn't processing other threads. In Task Manager, expect this process to account for the majority of processor time unless the system is very busy processing. 

Note: Any malware can be named anything - so you should check where the files of the running processes are located on your disk. If a "non-Microsoft" .exe file is located in the C:Windows or C:WindowsSystem32 folder, then there is a high risk for a virus, spyware, trojan or worm infection!