Are you familiar with how Security labels can be used to control access to data? If you’re planning on taking the Security+ exam, it’s something you might like to review. For example, can you answer this sample practice test question?
Q. A security administrator needs to implement an access control system that will protect data based on the following matrix.
| Document Type | Security Level | Security Label |
| Employment documents | Confidential | Employee |
| Salary and Compensation Documents | Confidential | Payroll |
| Internal phone listing documents | Confidential | Employee |
(Note that this matrix only represents a subset of the overall requirements).
Which of the following choices would be the BEST solution to meet this requirement?
A. DAC
B. Trusted OS
C. Role-BAC
D. SCADA
The answer and explanation is available here.
The 601 Version of the Study Guide
The CompTIA Security+: Get Certified Get Ahead: SY0-601 Study GuideEach of the eleven chapters presents topics in an easy to understand manner and includes real-world examples of security principles in action.
You’ll understand the important and relevant security topics for the Security+ exam, without being overloaded with unnecessary details. Additionally, each chapter includes a comprehensive review section to help you focus on what’s important.
Over 300 realistic practice test questions with in-depth explanations will help you test your comprehension and readiness for the exam. The book includes:
- A 75 question pre-test
- A 75 question post-test
- Practice test questions at the end of every chapter.
Each practice test question includes a detailed explanation to help you understand the content and the reasoning behind the question. You’ll be ready to take and pass the exam the first time you take it.
If you plan to pursue any of the advanced security certifications, this guide will also help you lay a solid foundation of security knowledge. Learn this material, and you’ll be a step ahead for other exams. This SY0-601 study guide is for any IT or security professional interested in advancing in their field, and a must-read for anyone striving to master the basics of IT security.
Mandatory Access Control
The MAC model uses labels (sometimes referred to as sensitivity labels or security labels) to determine access. Security administrators assign labels to both subjects (users) and objects (files or folders). When the labels match, the system can grant a subject access to an object. When the labels don’t match, the access model blocks access.
Military units make wide use of this model to protect data. You may have seen movies where they show a folder with a big red and black cover page labeled “Top Secret.” The cover page identifies the sensitivity label for the data contained within the folder. Users with a Top Secret label (a Top Secret clearance) and a need to know can access the data within the Top Secret folder.
Need to know is an important concept to understand. Just because individuals have a Top Secret clearance, it doesn’t mean they should automatically have access to all Top Secret data. Instead, access is restricted based on a need to know. Need to know is similar in concept to the principle of least privilege, but it only applies to data and data permissions. In contrast, the principle of least privilege applies to permissions and rights.
Security-enhanced Linux (SELinux) is one of the few operating systems using the mandatory access control model. SELinux was specifically created to demonstrate how mandatory access controls can be added to an operating system. In contrast, Windows operating systems use the discretionary access control model.
Labels and Lattice
The MAC model uses different levels of security to classify both the users and the data. These levels are defined in a lattice. The lattice can be a complex relationship between different ordered sets of labels. These labels define the boundaries for the security levels.
The following figure shows how the MAC model uses a lattice to divide access into separate compartments based on a need to know. The lattice starts by defining different levels of Top Secret, Secret, Confidential, and For Official Use. Each of these labels defines specific security boundaries. Within these levels, the lattice defines specific compartments. For example, the Top Secret level includes compartments labeled Nuclear Power Plant, 007, and Happy Sumo.
Imagine that Homer has a Top Secret clearance with a Nuclear Power Plant label. This gives him access to data within the Nuclear Power Plant compartment. However, he does not have access to data in the 007 or Happy Sumo compartment unless he also has those clearances (and associated labels).
Higher-level clearances include lower-level clearances. For example, because Homer has a Top Secret clearance, he can be granted access to Secret and lower-level data. Again though, he will only be able to access data on these lower levels based on his need to know.
As another example, imagine that Lisa has a Secret level clearance. Administrators can grant her access to data on the Secret level and lower levels, based on her need to know. For example, they might grant her access to the Research data by assigning the Research label to her, but not necessarily grant her access to Three-Eyed Fish or Legal Issues data. However, they cannot grant her access to any data on the Top Secret level.
Trusted OS
A trusted operating system (trusted OS) meets a set of predetermined requirements with a heavy emphasis on authentication and authorization. The overall goal of a trusted operating system is to ensure that only authorized personnel can access data based on their permissions.
Additionally, a trusted operating system prevents any modifications or movement of data by unauthorized entities. With this in mind, a trusted OS helps prevent malicious software (malware) infections because it prevents malicious or suspicious code from executing.
A trusted OS meets a high level of security requirements imposed by a third party. For example, the Common Criteria for Information Technology Security Evaluation (or simply Common Criteria) includes requirements for a trusted OS. Operating systems that meet these requirements can be certified as trusted operating systems.
Remember this
The MAC model uses sensitivity labels for users and data. It is commonly used when access needs to be restricted based on a need to know. Sensitivity labels often reflect classification levels of data and clearances granted to individuals. A trusted OS will typically use a MAC model.
Q. A security administrator needs to implement an access control system that will protect data based on the following matrix.
| Document Type | Security Level | Security Label |
| Employment documents | Confidential | Employee |
| Salary and Compensation Documents | Confidential | Payroll |
| Internal phone listing documents | Confidential | Employee |
(Note that this matrix only represents a subset of the overall requirements).
Which of the following choices would be the BEST solution to meet this requirement?
A. DAC
B. Trusted OS
C. Role-BAC
D. SCADA
B is the correct answer. A trusted operating system (trusted OS) meets a set of predetermined requirements with a heavy emphasis on authentication and authorization. It can be used to implement a form of mandatory access control (MAC) that uses labels to provide multi-level security.
Note that all of the documents in the matrix are classified as Confidential. However, the additional labels of Employee and Payroll create a deeper matrix. For example, only personnel with the Confidential clearance and are assigned the Payroll label (Confidential-Payroll) can access Salary and Compensation documents.
A is not correct. A discretionary access control (DAC) model as an owner, and the owner establishes access for the objects. It does not assign permissions with labels.
C is not correct. A role-based access control (role-BAC) model uses roles or groups to assign rights and permission, not labels.
D is incorrect. SCADA (supervisory control and data acquisition) is not related to this question at all and merely tests your knowledge of acronyms.
What is this question really asking?
What is the question really asking?
On the surface, this is a simple question asking about what access control model supports labels. The answer is MAC.
However, this isn’t an available answer.
From a deeper perspective, the question is asking “Do you know that a trusted OS typically uses MAC model?”
Even if you don’t, you should be able to arrive at the correct answer by eliminating the other answers. Neither DAC, nor Role-BAC use labels. Further, SCADA is completely unrelated to the question. Eliminate those answers and you’ve come to the correct one.
