Explanation
Rule-based access control is a type of non-discretionary access control because this access is determined by rules and the subject does not decide what those rules will be, the rules are uniformly applied to ALL of the users or subjects. In general, all access control policies other than DAC are grouped in the category of non-discretionary access control (NDAC).As the name implies, policies in this category have rules that are not established at the discretion of the user. Non-discretionary policies establish controls that cannot be changed by users, but only through administrative action. Both Role Based Access Control (RBAC) and Rule Based Access Control (RuBAC) fall within Non Discretionary Access Control (NDAC).If it is not DAC or MAC then it is most likely NDAC. IT IS NOT ALWAYS BLACK OR WHITE - The different access control models are not totally exclusive of each others.MAC is making use of Rules to be implemented.However with MAC you have requirements above and beyond having simple access rules.The subject would get formal approval from management, the subject must have the proper security clearance, objects must have labels/sensitivity levels attached to them,subjects must have the proper security clearance. If all of this is in place then you have MAC. BELOW YOU HAVE A DESCRIPTION OF THE DIFFERENT CATEGORIES: MAC = Mandatory Access Control - Under a mandatory access control environment, the system or security administrator will define what permissions subjects have on objects.The administrator does not dictate users access but simply configure the proper level of access as dictated by the Data Owner. The MAC system will look at the Security Clearance of the subject and compare it with the object sensitivity level or classification level.This is what is called the dominance relationship. The subject must DOMINATE the object sensitivity level.Which means that the subject must have a security clearance equal or higher than the object he is attempting to access. MAC also introduce the concept of labels.Every objects will have a label attached to them indicating the classification of the object as well as categories that are used to impose the need to know (NTK) principle.Even thou a user has a security clearance of Secret it does not mean he would be able to access any Secret documents within the system.He would be allowed to access only Secret document for which he has a Need To Know, formal approval, and object where the user belong to one of the categories attached to the object. If there is no clearance and no labels then IT IS NOT Mandatory Access Control. Many of the other models can mimic MAC but none of them have labels and a dominance relationship so they are NOT in the MAC category. NISTR-7316 Says: Usually a labeling mechanism and a set of interfaces are used to determine access based on the MAC policy; for example, a user who is running a process at the Secret classification should not be allowed to read a file with a label of Top Secret. This is known as the "simple security rule," or "no read up." Conversely, a user who is running a process with a label of Secret should not be allowed to write to a file with a label of Confidential. This rule is called the "*-property" (pronounced "star property") or "no write down." The *-property is required to maintain system security in an automated environment. A variation on this rule called the "strict *- property" requires that information can be written at, but not above, the subject’s clearance level. Multilevel security models such as the Bell-La Padula Confidentiality and Biba Integrity models are used to formally specify this kind of MAC policy. DAC = Discretionary Access Control DAC is also known as:Identity Based access control system. The owner of an object is define as the person who created the object.As such the owner has the discretion to grant access to other users on the network. Access will be granted based solely on the identity of those users. Such system is good for low level of security.One of the major problem is the fact that a user who has access to someone`s else file can further share the file with other users without the knowledge or permission of the owner of the file.Very quickly this could become the wild wild west as there is no control on the dissimination of the information. RBAC = Role Based Access Control RBAC is a form of Non-Discretionary access control. Role Based access control usually maps directly with the different types of jobs performed by employees within a company. For example there might be 5 security administrator within your company.Instead of creating each of their profile one by one, you would simply create a role and assign the administrators to the role.Once an administrator has been assigned to a role, he will IMPLICITLY inherit the permissions of that role. RBAC is great tool for environment where there is a a large rotation of employees on a daily basis such as a very large help desk for example. RBAC or RuBAC =Rule Based Access Control RuBAC is a form of Non-Discretionary access control. A good example of a Rule Based access control device would be a Firewall.A single set of rules is imposed to all users attempting to connect through the firewall. NOTE FROM CLEMENT: Lot of people tend to confuse MAC and Rule Based Access Control. Mandatory Access Control must make use of LABELS.If there is only rules and no label, it cannot be Mandatory Access Control.This is why they call it Non Discretionary Access control (NDAC). There are even books out there that are WRONG on this subject.Books are sometimes opiniated and not strictly based on facts. In MAC subjects must have clearance to access sensitive objects.Objects have labels that contain the classification to indicate the sensitivity of the object and the label also has categories to enforce the need to know. Today the best example of rule based access control would be a firewall.All rules are imposed globally to any user attempting to connect through the device. This is NOT the case with MAC. I strongly recommend you read carefully the following document: NISTIR-7316 at http://csrc.nist.gov/publications/nistir/7316/NISTIR-7316.pdf It is one of the best Access Control Study document to prepare for the exam.Usually I tell people not to worry about the hundreds of NIST documents and other reference.This document is an exception.Take some time to read it. Reference(s) used for this question: KRUTZ, Ronald L. & VINES, Russel
D., The CISSP Prep Guide: Mastering the Ten Domains of Computer Security, 2001, John Wiley & Sons, Page 33. and NISTIR-7316 at http://csrc.nist.gov/publications/nistir/7316/NISTIR-7316.pdf and Conrad, Eric; Misenar, Seth; Feldman, Joshua (2012-09-01). CISSP Study Guide (Kindle Locations 651-652). Elsevier Science (reference). Kindle Edition.