Risk assessment quantifies or qualifies risks based on different values or judgments. If you’re planning to take the Security+ exam, you should have a basic understanding of risk assessment best practices such as using metrics to identify risk.
Here’s a sample practice test question:
Q. A security expert is attempting to identify the number of failures a web server has in a year. Which of the following is the expert MOST likely identifying?
A. SLE
B. MTTR
C. ALE
D. MTTF
Can you answer the question? More, do you know why the correct answer is correct and the incorrect answers are incorrect? The answer and explanation is available at the end of this post.
Documenting the Assessment
The final phase of the risk assessment is the report. This identifies the risks discovered during the assessment and the recommended controls. As a simple example, a risk assessment on a database-enabled web application may discover that it’s susceptible to SQL injection attacks. The risk assessment will then recommend rewriting the web application with input validation techniques or stored procedures to protect the database.
Management uses this to decide which controls to implement and which controls to accept. In many cases, a final report documents the managerial decisions. Of course, management can decide not to implement a control, but instead accept a risk.
Think how valuable this report will be for an attacker. They won’t need to dig to identify vulnerabilities or controls. Instead, the report lists all the details. Even when management approves controls to correct the vulnerabilities, it may take some time to implement them. Because of this, the results of a risk assessment are highly protected. Normally, only executive management and security professionals will have access to these reports.
Using Metrics to Identify Risk
When identifying risks associated with hardware, security experts and administrators use several metrics. These include:
- Mean time between failures (MTBF). The mean time between failures (MTBF) provides a measure of a system’s reliability and is usually represented in hours. More specifically, the MTBF identifies the average (the arithmetic mean) time between failures. Higher MTBF numbers indicate a higher reliability of a product or system. Administrators and security experts attempt to identify the MTBF for critical systems with a goal of predicting potential outages.
- Mean time to failure (MTTF). The mean time to failure (MTTF) is the length of time you can expect a device to remain in operation before it fails. It is similar to MTBF, but the primary difference is that the MTBF metric indicates you can repair the device after it fails. The MTTF metric indicates that you will not be able to repair a device after it fails.
- Mean time to recover (MTTR). The mean time to recover (MTTR) identifies the average (the arithmetic mean) time it takes to restore a failed system. In some cases, people interpret MTTR as the mean time to repair, and both mean essentially the same thing. Organizations that have maintenance contracts often specify the MTTR as a part of the contract. The supplier agrees that it will, on average, restore a failed system within the MTTR time. The MTTR does not provide a guarantee that it will restore the system within the MTTR every time. Sometimes it may take a little longer and sometimes it may be a little quicker, with the average defined by the MTTR.
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. A security expert is attempting to identify the number of failures a web server has in a year. Which of the following is the expert MOST likely identifying?
A. SLE
B. MTTR
C. ALE
D. MTTF
Answer is C. Annualized loss expectancy (ALE) is part of a quantitative risk assessment and is the most likely answer of those given. It is calculated by multiplying the single loss expectancy times the annualized rate of occurrence (ARO).
Mean time to recover (MTTR) and mean time to failure (MTTF) do not identify the number of failures in a year.
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