What is Botnet in Cybersecurity and How Botnet Attack Works?

A botnet is a network of compromised computers that is used by hackers to launch DoS or DDoS attacks. When attackers use these botnet devices to perform malicious activities, it is called a botnet attack.

According to a security brief in NZ 2024, botnet-driven Distributed Denial of Service (DDoS) attacks increased by 82%, rising from 90,000 incidents in 2023 to over 165,000 in 2024.

In this article, we have explained the meaning of botnet, how a botnet attack works, its examples, and strategies to mitigate botnet attack risks. Furthermore, if you are interested in getting into the cybersecurity field, you can check out our Cybersecurity courses.

What is a Botnet?

A bot refers to a compromised device, and a botnet is a network of such compromised devices. These botnets are managed through command and control (C2) servers. They are commonly used for activities like DDoS attacks, data theft, and cryptocurrency mining.

Devices in botnets are infected with malware and controlled by an attacker, called a "bot-herder." While botnets can serve legitimate functions, like managing chat rooms or tracking game points, they become dangerous when misused. 

Become Certified Ethical HackerJoin our online training class on ethical hacking.Explore course

What is a Botnet Attack?

A botnet attack is a type of cyberattack carried out using bots or zombies, devices of a botnet. These devices are remotely controlled by an attacker to carry out malicious attacks.

Botnet attacks are very dangerous because a botnet can contain thousands or millions of infected devices, which makes it difficult to stop. The attacker uses a command-and-control (C&C) server to coordinate the bots, often without the device owners knowing their systems are being misused. 

Types of Botnet Attacks

Some common types of botnet attacks are:

Different Models of Botnet Structure

A botnet model defines how infected devices (bots) are controlled. There are different models of botnets based on the network’s efficiency, scalability, and stealth. The three main botnet models are client/server, hierarchical, and peer-to-peer (P2P).

1. Client/Server Model: In this traditional setup, a central Command and Control (C&C) server directs all bots. It’s easy to manage but vulnerable, because if the server is taken down, the botnet collapses. There are two topology variations in this model:

● Star Topology: All bots connect to one central server, simple, but easily traceable.

● Multi-Server Topology: Uses multiple servers for redundancy and resilience.

2. Hierarchical Model: This model adds layers in bot management. A main server controls mid-level bots, which manage lower-level bots. It offers anonymity for the attacker, is scalable, and is resistant to partial shutdowns.

3. Peer-to-Peer (P2P) Model: In this decentralized design, every bot acts as both client and server. Bots exchange commands among themselves, making the network highly resilient with no central point of failure. It is hard to detect or dismantle.

How is a Botnet Created?

A botnet is created in a multi-step process, where hackers first gain access to a system and maintain their control without getting detected. Here is a simplified process on how hackers create a botnet.

1. Hackers exploit software flaws, unsecured devices, or human error (e.g., phishing, drive-by downloads) to spread malware.

2. The malware installs silently, hiding in background processes, disabling security tools, and connecting to a command-and-control (C&C) server.

3. Infected devices become bots, unaware they're now part of a botnet.

4. Once enough bots are active, the attacker issues remote commands to launch DDoS attacks, steal data, mine cryptocurrency, or spread further infections.

5. Many botnets self-update and expand autonomously.

Also, read about Network Security Tools

How are Botnets Used for Cyber Attacks?

Botnets are used in cyber attacks by turning infected devices into remote-controlled tools. Hackers use these compromised devices to flood websites with traffic (DDoS attacks), send spam emails, steal personal data, or spread malware.

Since botnets can include thousands of devices, they can cause major disruptions without the real owners even knowing about it. The attacker controls the botnet through a central system (Command and Control (C&C) channel), sending commands to all the bots at once. This makes the attack powerful, fast, and hard to trace. 

A botnet can be used to carry out various cyber attacks, like:

1. DNS manipulation (DnsMAP): Redirecting domains to a bot-herder-controlled IP.

2. Web injection: Adding harmful code to websites the bot visits.

3. Web filters: Bypassing restrictions or capturing screenshots.

4. Web redirection: Redirecting users to malicious sites.

What Makes a Botnet Attack Dangerous?

A botnet attack is dangerous mainly because of its scale, stealth, and impact. Hackers control thousands and millions of infected computers to launch powerful cyber attacks like DDoS, which can shut down websites or services.

A botnet attack is very hard to trace because it comes from many sources, and since infected devices often appear normal, the attack can go unnoticed for a long time, making it even more harmful.

Botnets are very versatile and can be used for various cyber crimes like stealing data, sending spam emails, or spreading malware to increase botnet without users knowing. Their ability to cause widespread damage quickly makes botnet attacks a serious cybersecurity threat.

Botnet Examples in Real Life

Here are a few examples of popular botnet attacks in the world: 

1. Necurs Botnet (2017): This botnet was responsible for massive spam and phishing campaigns, impacting systems in India by spreading malware like Locky and Dridex.

2. Mirai Botnet (2016): Aimed at IoT devices, the Mirai botnet caused major DDoS attacks globally, affecting small businesses in India due to the hijacking of unsecured devices.

3. Andromeda Botnet (2017): Known for distributing a variety of malware, including ransomware and banking trojans, Andromeda also targeted users in India.

Is Your Computer Part of a Botnet?

As we know, the owners of zombie computers in a botnet are unaware of it. But how can you find out if your system is compromised and is being used for malicious activities? Here are some signs that your computer may be part of a botnet:

● Your system becomes sluggish or unresponsive without a clear reason.

● Internet usage spikes even when you're not actively browsing or downloading.

● Suspicious or unfamiliar applications appear in your task manager or startup list.

● Friends report receiving strange emails from your account.

● Your system crashes or shows error messages more often than usual.

How to Safely Remove Your Computer from a Botnet?

If your computer is infected and is being used in a botnet, follow the given tips to recover from botnet attack and gain control over it.

● Disconnect your PC from the internet by unplugging your network cable or disabling Wi-Fi to stop the botnet from communicating with your device.

● Restart your computer in Safe Mode to prevent malware from running during startup.

● Use a trusted antivirus or anti-malware tool (like Malwarebytes, Bitdefender, or Windows Defender) to detect and remove malicious software.

● Uninstall any unknown or suspicious applications from your system via Control Panel or Settings.

● You can reinstall a new OS or try updating the existing OS to patch any old vulnerabilities.

How to Defend Against Botnet Attacks

Botnet attacks can create serious damage to individuals and organizations, so it is essential to strengthen your defense against botnet attacks. Below we have provided a table summarizing how to detect and protect yourself from a botnet attack.

Conclusion

Botnets represent a serious and growing threat in the world of cybersecurity. By silently hijacking thousands of devices, attackers can launch powerful and disruptive attacks with minimal effort and high impact.

Understanding how botnets operate and recognizing the signs of infection is essential for individuals and organizations alike. With proper awareness, strong security practices, and timely action, it's possible to detect, prevent, and recover from botnet-related threats.