Malware is a term used to describe any malicious software that is designed to cause harm to a computer system, network, or device. Malware is a severe threat to individuals and organizations alike. Malicious actors can use malware to steal sensitive data, damage systems, and disrupt operations. Penetration testers and red teams often face the challenge of detecting and analyzing malware to assess an organization’s security posture.

In this article, we will introduce the basic concepts of malware analysis and discuss the different types of malware, their characteristics, and their attack vectors. We will also explore the tools and techniques used in malware analysis, including static and dynamic analysis, and some practical examples.

Types of Malware

Malware comes in many forms and can have different characteristics and capabilities. Some of the most common types of malware include:

  1. Viruses: A virus is a malware that infects a host file or program and replicates itself when that file or program is executed. Viruses can be spread through email attachments, infected websites, or shared files.
  2. Worms: A worm is a type of malware that can replicate itself and spread across networks and devices without user interaction. Worms can exploit vulnerabilities in software and operating systems to propagate.
  3. Trojans: A Trojan is a type of malware that disguises itself as a legitimate program or file and tricks the user into executing it. Trojans can be used to steal data, create backdoors, or provide remote access to a compromised system.
  4. Ransomware: Ransomware is malware that encrypts files on a system and demands payment in exchange for the decryption key. Ransomware can be spread through infected email attachments or links, software updates, or drive-by downloads.
  5. Adware: Adware is malware that displays unwanted advertisements or pop-ups on a user’s device. Adware can be installed through bundled software or infected websites.

Characteristics of Malware

Malware can have different characteristics depending on its type and purpose. Some common characteristics of malware include:

  1. Persistence: Malware can be designed to remain on a system even after a reboot or antivirus scan.
  2. Polymorphism: Polymorphic malware can change its code or signature to evade detection by antivirus software.
  3. Stealth: Malware can use techniques such as rootkits, backdoors, and obfuscation to hide its presence and activity.
  4. Network communication: Malware can communicate with remote or command-and-control (C2) servers to receive commands or exfiltrate data.
  5. Anti-analysis: Malware can detect when it is being analyzed and modify its behavior or code to evade detection.

Attack Vectors

Malware can be spread through different attack vectors, including:

  1. Email: Malware can be spread through email attachments or links in phishing emails.
  2. Social engineering: Malware can be spread through social engineering techniques, such as tricking the user into downloading a fake software update or clicking on a malicious link.
  3. Drive-by downloads: Malware can be spread through infected websites that exploit vulnerabilities in the user’s browser or plugins.
  4. USB devices: Malware can be spread through infected USB devices or external hard drives.

Malware Analysis Techniques

Malware analysis dissects malware to understand its behavior, characteristics, and purpose. Malware analysis can be divided into two categories: static and dynamic.

Static Analysis

Static analysis involves examining the malware code and file structure without actually executing the malware. Static analysis can include disassembly, decompilation, and code analysis. One tool commonly used for static analysis is IDA Pro. IDA Pro is a disassembler and debugger that allows analysts to examine the code of a binary file, identify functions, and analyze the program’s control flow.

Another tool that is commonly used for static analysis is PEiD. PEiD is a tool that analyzes the headers of a Windows executable file to identify if it has been packed or obfuscated.

Dynamic Analysis

Dynamic analysis involves executing the malware in a controlled environment and analyzing its behavior. Dynamic analysis can include techniques such as sandboxing, memory analysis, and network traffic analysis. One tool commonly used for dynamic analysis is Cuckoo Sandbox. Cuckoo Sandbox is an automated malware analysis tool that can run malware in a virtual environment and capture its behavior, network activity, and system changes.

Another tool that is commonly used for dynamic analysis is Wireshark. Wireshark is a network protocol analyzer that can capture and analyze malware-generated network traffic.

Malware Analysis Process

The process of analyzing malware can be broken down into several steps:

  1. Identification: The first step in malware analysis is identifying the malware. This can be done by analyzing the characteristics and behavior of the malware, such as its file name, file size, and network activity.
  2. Extraction: The next step is extracting the malware from the infected system. This can be done using antivirus software or manual analysis to identify and isolate the malware.
  3. Analysis: The analysis involves examining the malware to identify its behavior, characteristics, and purpose. This can be done using static, dynamic, or both analysis techniques.
  4. Reverse Engineering: Reverse engineering involves breaking down the malware’s code to identify how it works and what it does. This can be done using disassemblers, decompilers, and debuggers.
  5. Reporting: The final step in malware analysis is reporting the findings. This can include documenting the behavior and characteristics of the malware, identifying any vulnerabilities or weaknesses, and providing recommendations for mitigation and prevention.

Real-World Examples

Let’s take a look at some real-world examples of malware and how they were analyzed:

  1. WannaCry: WannaCry is a ransomware that spread globally in May 2017, infecting hundreds of thousands of computers. The malware used a vulnerability in the Windows SMB protocol to spread across networks. Malware analysts used a combination of static and dynamic analysis to identify the malware’s behavior and develop a decryption tool.
  2. Stuxnet: Stuxnet is a worm discovered in 2010 and targeted industrial control systems in Iran. The malware used multiple zero-day exploits to infect systems and modify the behavior of industrial controllers. Malware analysts used reverse engineering to identify the code and behavior of the malware and determine its purpose.

Conclusion

Malware analysis is a critical skill for penetration testers and red teams, as it allows them to identify and assess an organization’s security posture. Analysts can effectively detect and analyze malware by understanding the different types of malware, their characteristics, and attack vectors, as well as the tools and techniques used in malware analysis. While malware analysis can be complex and time-consuming, it is essential for identifying and mitigating the threats posed by malicious actors.