Overview of Botnet Malware: Structures, Types of Botnet Attacks, & More

Have you come across unexplained changes in your computer system, network, or an application you use? If there is an application that you cannot close, or if you are using the Windows operating system and Task Manager displays a program that you do not know about, there must be a botnet behind it. Botnet malware in cyber security is implanted on targeted computer systems or servers for ill-intended attacks. It has become a cybersecurity threat because its design has become more sophisticated, making it difficult to detect, track, and remove. 

This blog discusses the meaning of botnet and gives an overview of various types of botnet attacks and control structures to understand how a botnet operates.

What is a Botnet?

The word ‘botnet’ is an amalgamation of two words, ‘robot’ and ‘network’. A single device that has been infected with malware is referred to as a ‘bot’. A botnet meaning can be understood as a group of computer systems, servers, or websites that get infected with malware. Malicious attackers who capture and control a botnet are known as ‘botnet herders’. A botnet herder either directly infects the targeted computer system with the botnet or allows it to run silently on the system while waiting for instructions from the botnet herder. 
To learn more, utilize an online course on ethical hacking to protect and secure websites, computer systems, or networks like a pro.

Types of Botnet Attacks and Their Purposes

The main purpose of a botnet attack is to launch malicious activities and make a profit in an unethical way. Let’s understand the malicious intentions behind creating a botnet:

• Distributed Denial of Service (DDoS) Attacks: The botnet is used to send a high volume of traffic to a single target to overwhelm the target server/network. Thereby, causing the network to crash or become otherwise unavailable to legitimate users.
• Theft of Credentials: Botnets can also be used to steal data from compromised systems and devices to gain unauthorized access to online accounts, financial information, or sensitive data.
• Email Spamming: Botnets enable attackers to send out huge volumes of spam emails to distribute malware into the system or device or even conduct phishing campaigns.
• Running Fraudulent Ads: Botnets can generate non-human traffic on a website or web application. Therefore, a botnet can easily flood a website or an application with online advertisements, enticing users to click on them. This way, the botnet herders unethically profit from the click-through rates on advertisements.
• Ransomware Attacks: The importance of cybersecurity in terms of preventing malware and botnet attacks on a banking system or personal account has been threatened. A ransomware attack by a botnet involves the use of malicious code to encrypt data on a system or device, which is then held hostage until a ransom is paid. 
• Cryptocurrency Mining: A botnet attacks a network of computers to generate or “mine” cryptocurrencies such as Bitcoin. The computers in the botnet work together to solve complex mathematical puzzles, and if they succeed, the miners receive a certain amount of cryptocurrency. This can be a financial incentive for botnet herders, as they can profit from their botnet’s mining activities.
• Proxy Network Attacks: Botnets can set up proxy networks. This allows the botnet herder to conceal their identity and mask their Internet activities, such as accessing blocked websites, performing hacking, or sending malicious traffic. 
• Sponsored Botnet Attacks by a State/Group: In this digital world, botnets are an easily available option for countries or groups to launch malicious attacks. This type of botnet attack has political or ideological motives to change online discourse or influence public opinions.

Botnet Control Structures

Learning to catch a botnet herder is one of the most rewarding job tasks for a career in cybersecurity. For an aspiring cybersecurity professional, it is vital to gain all cybersecurity skills including the ability to identify who botnet herders are and what control structures they use to launch an attack.

Let us understand them one by one. A botnet herder instructs and manipulates malicious activities on any network with the help of a botnet. There are potential attack vectors that enable a botnet herder to launch and control a malware attack, such as changing a targeted system’s IP address, setting up a proxy network, etc. Botnet herders can easily customize an attack – when to start, how to do it, and when to terminate it. 

There are mainly two types of control structures needed for a botnet to function:

1. Client/Server Botnet Model

This model is similar to the workstation, where a system of computers connects to a centralized server to manage the flow and access to information. Instead of a central server, this model has a command-and-control (CnC) center to administer a botnet attack. Through the CnC, the botnet receives instructions from the botnet herders. To update instructions for the compromised machines or devices within a botnet, an attacker easily alters the source content distributed to each botnet from a command center. This centralized command center can either be a device owned by the attacker or a device that has been compromised by the attacker.

There are three types of topologies for designing this type of model:

• Star Network Topology: In this type of topology, there is one command-and-control center to manage two or more botnets. The bots are connected to the command-and-control center in a star shape, with the center being the hub of the network. All communications between the bots and the command-and-control center are routed through the hub, allowing the attacker to monitor and control the activity of the bots.

• Muti-Server Network Topology: It is an architecture of a botnet in which multiple command-and-control (C&C) centers are used to manage two or more botnets. It provides more flexibility and scalability to the botnet by allowing the attackers to divide it into multiple clusters. Each cluster is managed by a separate CnC center, which allows attackers to launch large-scale coordinated attacks from multiple locations.

• Hierarchical Network Topology: This type of topology is composed of multiple command-and-control (C&C) centers and is organized in a hierarchical structure. Each botnet is managed by a single CnC center, which is connected to a higher-level CnC center. The higher-level CnC center is responsible for managing and administering all the lower-level CnC centers. 

2. Peer-to-Peer Botnet Model

The peer-to-peer botnet model is a type of botnet model in which multiple computers are connected in a decentralized network. It is a decentralized network of trusted peer-to-peer botnets. Unlike the client/server botnet model, there is no central command-and-control (CnC) center. Instead, the computers in the network communicate directly with each other in a peer-to-peer fashion. The bots in the network can receive commands and instructions from any other bot in the network, allowing attackers to launch distributed attacks. 

Botnet Malware Removal Strategies

There are a few ways to protect devices and networks from becoming botnets, such as:

• Identification of the Command-and-Control Centers: Once the CnC centers are identified, they can be easily disabled. It can turn the entire botnet offline and make it unfunctional. 

• Botnet Removal in Individual Devices: For personal or individual devices, the following measures should be taken to protect them from a botnet attack:
  • Install antivirus software.
  • Reinstall and renew antivirus software when it expires from a safe backup.
  • Format the entire system and start using it afresh, all clean and safe from any malware.
• IoT Device Botnet Removal Strategy: Either by running a factory reset or flashing the firmware.

Conclusion

Launching a botnet malware attack escalates the risk of privacy and the leak of sensitive data from a system or network. By taking proactive steps to prevent any harmful attack, any server, system, or network can be protected. It is easier to launch a botnet attack to cause any sort of disruption on a network because it is an inexpensive and efficient option for botnet herders. Protect your systems with the right antivirus software installed.

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