A method and device to control the access to a data memory space of a computer system by an active process stored in a program space of the system. When the active process attempts to perform an operation on a part of the data memory space the method or device controls the access to the part of the data memory space by comparing a dynamic attribute linked to the active process to an attribute linked to the part of the data memory space the process is attempting access. The value of the dynamic attribute is updated according to the present and previous status of the active process.