Reverse Engineering in Malware

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Reverse engineering techniques allow security experts to decompile malware to discover what it’s doing. Unfortunately, criminals often use techniques to make it more difficult for the security experts to reverse engineer some types of malware. This is important to know if you’re planning to take certification exam such as Security+.

As an example, see if you answer this sample Security+ practice test question.

Q. Which of the following types of malware is the MOST difficult to reverse engineer?

A. Logic bomb

B. Trojan

C. Armored virus

D. Ransomware

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.

Security+ Practice Test Questions

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Over 440 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.

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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 - 100 random questions. View 100 random questions from the full test bank similar to how the Security+ exam has a potential maximum of 100 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.

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INCLUDES QUESTIONS TO HELP YOU PREPARE

FOR THE NEW PERFORMANCE BASED QUESTIONS 

Bonus - Performance Based Questions

Additional Security+ questions to help you prepare for the new performance based questions. These are included with the full bank of Security+ practice test questions and are divided into different sections. For example, you'll have access to the following links:

- Performance Based Question - Set 1

You'll see a graphic explaining what you might be required to do on the actual exam to match different types of security to mobile devices and servers in a data center. You'll then have two questions that test your knowledge and ability to correctly answer the questions. This question also includes a link to a graphic showing the end solution for the overall performance based question simulation.

- Performance Based Question - Set 2

You'll see a graphic explaining what you might be required to do on the actual exam to match different types of attacks with the name of the attack type. You'll then have five questions that test your knowledge and ability to correctly answer the questions. This question also includes a link to a graphic showing the end solution for the overall performance based question simulation.

- Performance Based Question - Set 3

You'll see a graphic showing a network with computers and servers separated by a firewall. The firewall is used to control traffic between the computers and users using rules within an access control list (ACL).  You'll have three questions that test your knowledge and ability to correctly identify the relevant components of the rule. The incorrect answers and explanation provide you with insight into how to correctly answer this type of question on the actual exam.

- Performance Based Question - Set 4

You'll see a graphic explaining what you might be required to do on the actual exam related to what a forensic analyst would do during an investigation. You'll then have two questions that test your knowledge and ability to correctly answer the questions. This question also includes a link to a graphic showing the end solution for the overall performance based question simulation.

- Performance Based Question - Set 5

You'll see a graphic explaining what you might be required to do on the actual exam to match protocols and ports. You'll then have seven questions that test your knowledge and ability to correctly answer the questions. This question also includes a link to a graphic showing the end solution for the overall performance based question simulation.

- Performance Based Question - Set 6

You'll see a list of security controls along with a graphic showing devices and locations within an organization, along with instructions on what you might be required to do on the actual exam to match the controls with the devices and locations. You'll then have four questions that test your knowledge and ability to correctly answer the questions. This question also includes a link to a graphic showing the end solution for the overall performance based question simulation.

- Performance Based Question - Set 7

You'll see a list of authentication methods and authentication factors along with instructions on what you might be required to do on the actual exam to match the authentication methods with the authentication factors. You'll then have six questions that test your knowledge and ability to correctly answer the questions. This set also includes a link to a graphic showing the end solution for the overall performance based question simulation.

- Performance Based Question - Set 8

You'll see a graphic explaining what you might be required to do on the actual exam to match different types of attacks with the name of the attack type. You'll then have five questions that test your knowledge and ability to correctly answer the questions. This is similar to Set 2 but expands on the possibilities. The set also includes a link to a page showing the end solution for the overall performance based question simulation.

New - Performance Based Question - Set 9

New questions recently added using a different testing engine. See a demo here. This set includes drag and drop and matching questions on ports.

New - Performance Based Question - Set 10

A random set of 20 performance-based questions using drag and drop, matching, sorting, and fill in-the blank. This set includes performance-based questions on RAID.

Get the full bank of Security+ (SYO-401) Practice Test Questions Here

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You might hear people use the term virus to describe all types of malware, but that isn’t accurate. A virus is a specific type of malware, and malware includes many other types of malicious software, including worms, logic bombs, Trojans, ransomware, rootkits, spyware, and more.

Malware is not software that you would knowingly purchase or download and install. Instead, it is installed onto your system through devious means. Infected systems give various symptoms, such as running slower, starting unknown processes, sending out email without user action, random reboots, and more.

Malware

Viruses

A virus is a set of malicious code that attaches itself to a host application. The host application must be executed to run, and the malicious code executes when the host application is executed. The virus tries to replicate by finding other host applications to infect with the malicious code. At some point, the virus activates and delivers its payload.

Typically, the payload of a virus is damaging. It may delete files, cause random reboots, join the computer to a botnet, or enable backdoors that attackers can use to access systems remotely. Some older viruses merely displayed a message at some point, such as “Legalize Marijuana!” Most viruses won’t cause damage immediately. Instead, they give the virus time to replicate first.

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Online access includes all of the content from the

CompTIA Security+: Get Certified Get Ahead: SY0-401 Study Guide

  • Introduction
  • About the exam (including types of questions and strategies for performance-based questions)
  • 100 question pre-assessment exam
  • Mastering Security Basics (full content from Chapter 1 of the study guide including the exam topic review and 20 practice test questions)
  • Exploring Control Types and Methods (full content from Chapter 2 of the study guide including the exam topic review and 20 practice test questions)
  • Understanding Basic Network Security (full content from Chapter 3 of the study guide including the exam topic review and 20 practice test questions)
  • Securing Your Network (full content from Chapter 4 of the study guide including the exam topic review and 20 practice test questions)
  • Securing Hosts and Data (full content from Chapter 5 of the study guide including the exam topic review and 20 practice test questions)
  • Understanding Malware and Social Engineering (full content from Chapter 6 of the study guide including the exam topic review and 20 practice test questions)
  • Identifying Advanced Attacks (full content from Chapter 7 of the study guide including the exam topic review and 20 practice test questions)
  • Managing Risk (full content from Chapter 8 of the study guide including the exam topic review and 20 practice test questions)
  • Preparing for Business Continuity (full content from Chapter 9 of the study guide including the exam topic review and 20 practice test questions)
  • Understanding Cryptography (full content from Chapter 10 of the study guide including the exam topic review and 20 practice test questions)
  • Exploring Operational Security (full content from Chapter 11 of the study guide including the exam topic review and 20 practice test questions)
  • 100 question post-assessment exam
  • Security+ Acronyms

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Test your readiness with these quality materials

Random 100-question tests

Random practice tests from the all of the practice test questions in the CompTIA Security+: Get Certified Get Ahead: SY0-401 Study Guide. All questions include explanations so you'll know why the correct answers are correct, and why the incorrect answers are incorrect.

34 Simulated Performance-based Questions

Eight sets of performance-based questions with multiple questions in each set. These questions help you understand and prepare for performance based questions.

22 Realistic Performance-based Questions

Two new sets of performance-based questions with a total of 22 questions. These new questions use a new testing engine that includes realistic drag and drop, matching, sorting, and fill in the blank questions.

Flashcard Set

  • 273 Security+ Flashcards to reinforce key testable concepts
  • 280 Security+ acronyms flashcards to help you master the required acronyms
  • 204 Security+ Remember This slides

Audio - SY0-401 Security+ Remember This Audio Files

Learn by Listening. Over one hour and 15 minutes of audio (MP3 downloads.)

Audio - SY0-401 Security+ Question and Answer Audio Files

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Audio from the end of chapter reviews from each of the chapters in the CompTIA Security+: Get Certified Get Ahead: SY0-401 Study Guide. Over one hour and 15 minutes of additional audio.

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Subnetting mini-tutorial that will help you answer two key question types:
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A user will often execute the virus (though unknowingly), but other times, an operating system will automatically execute it after user interaction. For example, when a user plugs in an infected USB drive, the system can execute the virus infecting the system. Note that not all malware needs user interaction to run. As an example, worms are self-replicating and do not need user interaction.

Operation Buckshot Yankee

William Lynn, a U.S. Deputy Secretary of Defense, wrote an article in the Foreign Affairs magazine that demonstrates the risk from USB drives. He indicated that this incident marked a turning point in the U.S. cyber defense strategy.

In 2008, the U.S. military suffered a significant data breach that they traced back to a USB flash drive. Apparently, a foreign intelligence agency developed malware and installed it on a USB drive. Someone, though no one seems to be saying who, inserted the USB drive into a military laptop somewhere in the Middle East. The malware quickly infected the system.

The malware continued to operate silently on the mobile system and ultimately infected the U.S. Central Command’s network, including both classified and unclassified systems. Reports indicate that attackers were able to transfer data from the network to foreign servers. Ultimately, the U.S. military discovered the malware and launched Operation Buckshot Yankee. They cleaned the virus off all systems and investigated the incident. It is clear that this was a major incident, even though it started from malware on a single USB drive.

I was working on a U.S. base in 2008 when a new rule came out that banned the use of all removable USB flash drives. There was no mention of Operation Buckshot Yankee at the time, but it was clear that they were serious about enforcing the rule. I know of one contractor who ignored the rule, plugged in a USB flash drive, and had an opportunity to upgrade his résumé the next day. He was fired.

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Armored Virus

When antivirus (AV) researchers discover a new virus, they typically attempt to reverse engineer the code. Application developers first write applications in a computer language, such as C, C++, and C#. Although these have specific syntax rules, they are easy to read by people who know the language. Developers then compile the code into an executable application. Reverse engineering code is the process of decompiling the executable application and analyzing the code to discover what it does.

Armored viruses use various techniques to make the reverse engineering process more difficult for the AV researchers. Some methods used by armored viruses are:

  • Complex code. Some armored viruses use confusing code specifically designed to mask what the virus is actually trying to do.
  • Encryption. Some compilers encrypt the code with the virus, making it more difficult to decompile. This code must first be decrypted before it can be decompiled.
  • Hiding. Some viruses attempt to hide their actual location by tricking AV software into thinking the file is located somewhere else.

Remember this

An armored virus uses one or more techniques to make it difficult to reverse engineer. Common techniques include using complex code, using encryption, or hiding the location.

CompTIA Security+ Study Guide

The 401 Version of the Study Guide

SY0-401 Study GuideThe CompTIA Security+: Get Certified Get Ahead: SY0-401 Study Guide is an update to the top-selling SY0-201 and SY0-301 study guides, which have helped thousands of readers pass the exam the first time they took it.

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Over 400 realistic practice test questions with in-depth explanations will help you test your comprehension and readiness for the exam. The book includes:

  • A 100 question pre-test
  • A 100 question post-test
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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.

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Q. Which of the following types of malware is the MOST difficult to reverse engineer?

A. Logic bomb

B. Trojan

C. Armored virus

D. Ransomware

Answer is C. An armored virus uses one or more techniques to make it difficult for antivirus researchers to reverse engineer it.

A logic bomb executes in response to an event, but it is often implemented with simple code.

A Trojan appears to be something beneficial, but it includes a malicious component.

Ransomware takes control of a user’s system or data and then demands payment as ransom.

See Chapter 6 of the CompTIA Security+: Get Certified Get Ahead: SY0-401 Study Guide for more information on malware and social engineering.

You may also want to view the blog post about Identifying Malware Threats.

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