QUESTION: 157 Topic: 1, Access Control

Which of the following is an example of discretionary access control?

Identity-based access control
Task-based access control
Role-based access control
Rule-based access control

Answer(s): A

Explanation:

An identity-based access control is an example of discretionary access control that is based on an individual's identity. Identity-based access control (IBAC) is access control based on the identity of the user (typically relayed as a characteristic of the process acting on behalf of that user) where access authorizations to specific objects are assigned based on user identity.
Rule Based Access Control (RuBAC) and Role Based Access Control (RBAC) are examples of
non-discretionary access controls.
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.
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 user's 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.
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.

Reference:

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
http://itlaw.wikia.com/wiki/Identity-based_access_control

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QUESTION: 158 Topic: 1, Access Control

Which of the following would be used to implement Mandatory Access Control (MAC)?

Clark-Wilson Access Control
Role-based access control
Lattice-based access control
User dictated access control

Answer(s): C

Explanation:

The lattice is a mechanism use to implement Mandatory Access Control (MAC)
Under Mandatory Access Control (MAC) you have:
Mandatory Access Control
Under Non Discretionary Access Control (NDAC) you have:
Rule-Based Access Control
Role-Based Access Control
Under Discretionary Access Control (DAC) you have:
Discretionary Access Control
The Lattice Based Access Control is a type of access control used to implement other access control method. A lattice is an ordered list of elements that has a least upper bound and a most lower bound. The lattice can be used for MAC, DAC, Integrity level, File Permission, and more
For example in the case of MAC, if we look at common government classifications, we have the following:
TOP SECRET
SECRET -----------------------I am the user at secret
CONFIDENTIAL
SENSITIVE BUT UNCLASSIFIED
UNCLASSIFIED
If you look at the diagram above where I am a user at SECRET it means that I can access document at lower classification but not document at TOP SECRET. The lattice is a list of ORDERED ELEMENT, in this case the ordered elements are classification levels. My least upper
bound is SECRET and my most lower bound is UNCLASSIFIED.
However the lattice could also be used for Integrity Levels such as:
VERY HIGH
HIGH
MEDIUM ----------I am a user, process, application at the medium level LOW
VERY LOW
In the case of of Integrity levels you have to think about TRUST. Of course if I take for example the the VISTA operating system which is based on Biba then Integrity Levels would be used. As a user having access to the system I cannot tell a process running with administrative privilege what to do. Else any users on the system could take control of the system by getting highly privilege process to do things on their behalf. So no read down would be allowed in this case and this is an example of the Biba model.
Last but not least the lattice could be use for file permissions:
RWX
RW ---------User at this level
R
If I am a user with READ and WRITE (RW) access privilege then I cannot execute the file because I do not have execute permission which is the X under linux and UNIX.
Many people confuse the Lattice Model and many books says MAC = LATTICE, however the lattice can be use for other purposes.
There is also Role Based Access Control (RBAC) that exists out there. It COULD be used to simulate MAC but it is not MAC as it does not make use of Label on objects indicating sensitivity and categories. MAC also require a clearance that dominates the object.
You can get more info about RBAC at:http://csrc.nist.gov/groups/SNS/rbac/faq.html#03
Also note that many book uses the same acronym for Role Based Access Control and Rule Based Access Control which is RBAC, this can be confusing.
The proper way of writing the acronym for Rule Based Access Control is RuBAC, unfortunately it is not commonly used.

Reference:

There is a great article on technet that talks about the lattice in VISTA:
http://blogs.technet.com/b/steriley/archive/2006/07/21/442870.aspx
also see:
KRUTZ, Ronald L. & VINES, Russel D., The CISSP Prep Guide: Mastering the Ten Domains of Computer Security, John Wiley & Sons, 2001, Chapter 2: Access control systems (page 33).
and
http://www.microsoft-watch.com/content/vista/gaging_vistas_integrity.html

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QUESTION: 159 Topic: 1, Access Control

Which type of attack involves impersonating a user or a system?

Smurfing attack
Spoofing attack
Spamming attack
Sniffing attack

Answer(s): B

Explanation:

A spoofing attack is when an attempt is made to gain access to a computer system by posing as an authorized user or system. Spamming refers to sending out or posting junk advertising and unsolicited mail. A smurf attack is a type of denial-of-service attack using PING and a spoofed address. Sniffing refers to observing packets passing on a network.

Reference:

KRUTZ, Ronald L. & VINES, Russel D., The CISSP Prep Guide: Mastering the Ten Domains of Computer Security, John Wiley & Sons, 2001, Chapter 3: Telecommunications and Network Security (page 77).

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QUESTION: 160 Topic: 1, Access Control

Which of the following is NOT an advantage that TACACS+ has over TACACS?

Event logging
Use of two-factor password authentication
User has the ability to change his password
Ability for security tokens to be resynchronized

Answer(s): A

Explanation:

Although TACACS+ provides better audit trails, event logging is a service that is provided with TACACS.

Reference:

KRUTZ, Ronald L. & VINES, Russel D., The CISSP Prep Guide: Mastering the Ten Domains of Computer Security, John Wiley & Sons, 2001, Chapter 3: Telecommunications and Network Security (page 121).

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