It’s common to implement several controls using a defense-in-depth strategy. If you’re planning to take the SY0-501 version of the Security+ exam, you should have a good understanding of frameworks, best practices, and secure configuration guides. This includes implementing defense-in-depth/layered security to protect assets.
For example, can you answer this question?
Q. After a recent attack on your organization’s network, the CTO is insisting that the DMZ uses two firewalls and they are purchased from different companies. Which of the following BEST describes this practice?
A. Single-layer security
B. Vendor diversity
C. Control diversity
D. Redundancy
More, do you know why the correct answer is correct and the incorrect answers are incorrect? The answer and explanation are available at the end of this post.
Implementing Defense in Depth
Defense in depth (also known as layered security) refers to the security practice of implementing several layers of protection. You can’t simply take a single action, such as implementing a firewall or installing antivirus software, and consider yourself protected. You must implement security at several different layers. This way, if one layer fails, you still have additional layers to protect you.
If you drive your car to a local Walmart, put a five-dollar bill on the dash, and leave the keys in the car and the car running, there is a very good chance the car won’t be there when you come out of the store. On the other hand, if you ensure nothing of value is visible from the windows, the car is locked, it has an alarm system, and it has stickers on the windows advertising the alarm system, it’s less likely that someone will steal it. Not impossible, but less likely.
You’ve probably heard this as “there is no silver bullet.” If you want to kill a werewolf, you can load your gun with a single silver bullet and it will find its mark. The truth is that there is no such thing as a silver bullet. (Of course, there is no such thing as a werewolf either.)
Applied to computers, it’s important to implement security at every step, every phase, and every layer. Information technology (IT) professionals can never rest on their laurels with the thought they have done enough and no longer need to worry about security.
Control diversity is the use of different security control types, such as technical controls, administrative controls, and physical controls. For example, technical security controls such as firewalls, intrusion detection systems (IDSs), and proxy servers help protect a network. Physical security controls can provide extra protection for the server room or other areas where these devices are located. Administrative controls such as vulnerability assessments and penetration tests can help verify that these controls are working as expected.
Vendor diversity is the practice of implementing security controls from different vendors to increase security. Many DMZs use two firewalls and vendor diversity dictates the use of firewalls from different vendors. For example, one firewall could be a Cisco firewall and the other one could be a Check Point firewall. If a vulnerability is discovered in one of these firewalls, an attacker might be able to exploit it. However, it’s unlikely that both firewalls would develop a vulnerability at the same time.
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.
Q. After a recent attack on your organization’s network, the CTO is insisting that the DMZ uses two firewalls and they are purchased from different companies. Which of the following BEST describes this practice?
A. Single-layer security
B. Vendor diversity
C. Control diversity
D. Redundancy
Answers is B. The chief technology officer (CTO) is recommending vendor diversity for the demilitarized zone (DMZ). Firewalls from different companies (vendors) provide vendor diversity. This also provides defense in depth or layered security, but not single-layer security.
Control diversity is the use of different controls such as technical, administrative, and physical.
Redundancy is the use of duplicate components for fault tolerance, but the two firewalls work together in the DMZ.
See Chapter 9 of the CompTIA Security+: Get Certified Get Ahead: SY0-501 Study Guide for more information on implementing controls to protect assets.
