Data Protection and Security

V

Access Control

V.II

Unix and Windows NT Access Control Overview

Least Privilege Principle:

Yet another important security principle is "least privilege principle" which simply says that each process should be given only the absolutely minimal set of privileges needed to successfully perform the desired task. Any additional, not needed, privilege possessed by a process increases the damage incurred if a vulnerability in the implementation of the process is exploited.

Unix did not follow this principle because as we mentioned earlier, the root user ID, typically made available to the system administrator, can do anything in the system. Many Unix programs cannot be installed by the user who does not have the root access and therefore should inherit all the privileges of the root. This is so because only root can perform actions like opening standard port numbers and intracting directly with peripheral hardware, etc. A solution to this problem (not implemented in Unix) is to grant a fine-grained access permissions for each process. e.g. if a process needs to open a standard port number, only that permission is given and nothing else.