Protecting Systems with Antivirus Software

Posted by in Security+ | 0 comments

If you’re planning on taking the Security+ exam, you should have a basic understanding of antivirus software and how it protects systems.

For example, can you answer this question?

Q. You manage a group of computers in an isolated network without Internet access. You need to update the antivirus definitions manually on these computers. Which of the following choices is the MOST important concern?

A. Running a full scan of the systems before installing the new definitions

B. Running a full scan of the systems after installing the new definitions

C. Ensuring the definition file hash is equal to the hash on the antivirus vendor’s website

D. Ensuring the update includes all signature definitions

More, do you know why the correct answer is correct and the incorrect answers are incorrect? Answer and explanation at end of this post.

Malware is a significant threat for any organization. Administrators commonly implement layered security, or a defense-in-depth plan, to protect against malware.

Using Antivirus Software

Anti-malware software provides protection against many types of malware. You’ll often hear the term antivirus software indicating it only protects against viruses. However, the lines have blurred. Viruses aren’t the only threats. Attackers have changed their methodologies using different types of malware, and antivirus software vendors have adapted by including methods to detect and block these new threats. Most antivirus software detects, blocks, and removes several different types of malware, such as viruses, Trojans, worms, rootkits, spyware, and adware.

Antivirus software provides real-time protection and can perform both scheduled and manual scans. The real-time protection continuously monitors the system. For example, when a user visits a website, antivirus software scans the downloaded website files and attempts to block malicious code. Similarly, when a user downloads or opens a file, antivirus software scans it before opening it. Scheduled scans occur regularly, such as once a week. If users or technicians detect suspicious activity, they can perform manual scans to check the system.

Antivirus software detects viruses using either signature-based detection or heuristic-based detection.

Signature-Based Detection

Viruses and other malware have known patterns. Signature files (also called data definition files) define the patterns, and the antivirus software scans files for matching patterns. When the software identifies a matching pattern, it reports it as an infection and takes action, such as deleting or quarantining the file.

A quarantined virus is not harmful to the system while it is in quarantine, but it’s still available for analysis. As an example, a security professional could release a quarantined virus into an unprotected but isolated virtual environment for research and study.

Antivirus Software

Malware developers constantly release new viruses, so it’s important to update signature definition files regularly. Most antivirus software includes the ability to automate the process of checking and downloading updated signature definition files. They typically check for updates several times a day.

It’s also possible to download and install signature files manually. Administrators do this when updating systems that do not have Internet access. When doing so, it’s important for administrators to ensure the signature file has not lost data integrity. They do so by comparing the hash of the signature file posted on the antivirus vendor’s website with the hash of the downloaded file.

To see an example of how to compare hashes, check out the Creating and Comparing Hashes Lab. You can access the online exercises at http://gcgapremium.com/labs/.

CompTIA Security+ Study Guide

The 501 Version of the Study Guide

The CompTIA Security+: Get Certified Get Ahead: SY0-501 Study Guide is an update to the top-selling SY0-201, SY0-301, and SY0-401 study guides, which have helped thousands of readers pass the exam the first time they took it.  It includes the same elements readers raved about in the previous three versions.

Each 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 SY0-501 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.

Kindle edition also available.

Heuristic-Based Detection

Some antivirus software includes heuristic-based detection. Heuristic-based detection attempts to detect viruses that were previously unknown and do not have signatures. This includes zero-day exploits.

Heuristic-based analysis runs questionable code in a sandbox or virtualized environment specifically designed to protect the live environment, while it observes its behavior. Most viruses engage in viral activities—actions that can be harmful, but are rarely performed by legitimate programs. The heuristic-based analysis detects these viral activities.

As an example, polymorphic malware adds variations to files when it creates copies. It’s highly unusual for any application to add variations in files like this, and heuristic methods are often successful at detecting polymorphic malware.

Remember this

Antivirus software detects and removes malware, such as viruses, Trojans, and worms. Signature-based antivirus software detects known malware based on signature definitions. Heuristic-based software detects previously unknown malware based on behavior.

File Integrity Checker and Antivirus Scanners

Some antivirus scanners use file integrity checkers to detect modified system files. A file integrity checker calculates hashes on system files as a baseline. It then periodically recalculates the hashes on these files and compares them with the hashes in the baseline. If the hashes are ever different, it indicates the system files have been modified. When an antivirus scanner detects a modified file, it sends an alert. Many times these alerts can detect rootkit infections.

When searching for rootkits, antivirus scanners also have the ability to inspect RAM.


Security+ Practice Test Questions

SY0-501 Practice Test Questions 

Over 300 realistic Security+ practice test questions

All questions include explanations so you'll know why the correct answers are correct,

and why the incorrect answers are incorrect.

Pass the Security+ Exam

the First Time You Take It

Multiple quiz formats to let you use these questions based on the way you learn.
  • Learn mode - randomized. View each of the questions in random order. Learn mode allows you to keep selecting answers until you select the correct answer. Once you select the correct answer, you'll see the explanation. Click here to see how learn mode works.
  • Learn mode - not randomized. View each of the questions in the same order. Use this if you want to make sure that you see all of the questions. Learn mode allows you to keep selecting answers until you select the correct answer. Once you select the correct answer, you'll see the explanation. Click here to see how learn mode works.
  • Test mode - randomized. View each of the questions in random order. In test mode, you can only see the correct answers and explanations after you complete the test. Click here to see how test mode works.
  • Test mode - not randomized. View each of the questions in the same order. In test mode, you can only see the correct answers and explanations after you complete the test. Click here to see how test mode works.
  • Test mode - 75 random questions. View 75 random questions from the full test bank similar to how the Security+ exam has a potential maximum of 75 multiple choice questions. In test mode, you can only see the correct answers and explanations after you complete the test. Click here to see how test mode works.

Get the full bank of SY0-501 Practice Test Questions Here

 SY0-501 Practice Test Questions


INCLUDES QUESTIONS TO HELP YOU PREPARE

FOR THE NEW PERFORMANCE BASED QUESTIONS 

Bonus - Performance Based Questions

Three sets of performance-based questions including over 30 questions. These questions show you what you can expect in the live exam. They include drag and drop, matching, sorting, and fill in the blank questions. See a demo here.

Bonus - Extra Practice Test Questions

New multiple-choice questions in the extra test bank. Questions are added occasionally. You can see what has been added recently here.

Get the full bank of Security+ (SYO-501) Practice Test Questions Here

Get the full bank of Security+ Practice Test Questions

Click here if you're looking for SY0-501 Full Study Package

Q. You manage a group of computers in an isolated network without Internet access. You need to update the antivirus definitions manually on these computers. Which of the following choices is the MOST important concern?

A. Running a full scan of the systems before installing the new definitions

B. Running a full scan of the systems after installing the new definitions

C. Ensuring the definition file hash is equal to the hash on the antivirus vendor’s website

D. Ensuring the update includes all signature definitions

Answer is C. When downloading files as important as antivirus definitions, it’s important to ensure they do not lose data integrity, and you can do so by verifying the hashes.

It’s not necessary to run a full scan either before or after installing new definitions, but the new definitions will help.

See Chapter 6 of the CompTIA Security+: Get Certified Get Ahead: SY0-401 Study Guide for information on protecting systems.

 

Leave a Comment

This site uses Akismet to reduce spam. Learn how your comment data is processed.

CompTIA Security+ Get Certified Get Ahead: SY0-501 Study Guide

Subscribe To Our Newsletter

Join our mailing list and get a free excerpt of the CompTIA Security+: Get Certified Get Ahead: SY0-501 Study Guide.  This excerpt includes the introduction and Chapter 1. 

You have Successfully Subscribed!

Get Certified Get Ahead is a participant in the Amazon Services LLC Associates Program,
an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to amazon.com.

Copyright © 2015 Get Certified Get Ahead. All Rights Reserved.