Many secure operating systems have some privileged processes or trusted processes which are always at risk of being hijacked by various attacks such as the buffer overflow attack.Once they are hijacked

the security of the whole system would be damaged.In this paper

a multi-protection domains process model is described which provides fine-grained kernel level protection for codes and data within process address space.The fine-grained internal protection of process can effectively prevent attackers from hijacking the whole process by damaging the process's data or codes.This paper offers two designs for this model and a prototype implementation of one of them.