What Is a Botnet, Its Architecture and How Does It Work?

What is a Botnet?

The words "robot" and "network" together give rise to the term Botnet. Botnet refers to a network of hijacked internet-connected devices that are installed with malicious codes known as malware. Each of these infected devices is known as Bots, and a hacker/cybercriminal known as the "Bot herder" remotely controls them. A bot is also called a zombie, and a botnet is referred to as a zombie army. 

The bot herder can direct every bot to carry out a coordinated illegal action from a single central location. A botnet can have several bots and thus allows the attacker to carry out large-scale attacks. Infected devices can acquire updates and modify their behavior easily and quickly since a remote attacker controls them. The bots are used to automate large-scale attacks, including data theft, server failure, malware propagation, spam email generation, and malicious traffic generation for distributed denial-of-service (DDoS) attacks.

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How Does a Botnet Work?

Now that you have a good understanding of what is a botnet, it’s time to dive deeper into learning how a botnet works. Below are the steps that are carried out to initiate a botnet attack:

• Prepping the Botnet Army: The first step in creating a botnet is to infect as many connected devices as possible, to ensure that there are enough bots to carry out the attack. It uses the computing power of the infected devices for tasks that remain hidden to the device owners. However, the fraction of bandwidth taken from a single machine isn't sufficient, and hence the Botnet combines millions of devices to carry out large-scale attacks. This way, it creates bots either by exploiting security gaps in software or websites or phishing emails. They often deploy botnets through a trojan horse virus.
• Establishing the connection: Once it hacks the device, as per the previous step, it infects it with a specific malware that connects the device back to the central botnet server. This way, it connects all the devices within the botnet network, and they are ready to execute the attack. A bot herder uses command programming to drive the bot's actions.
• Launching the attack: Once infected, a bot allows access to admin-level operations like gathering and stealing user data, reading and writing system data, monitoring user activities, performing DDoS attacks, sending spam, launching brute force attacks, crypto mining, and so on. 

Fig: Working of a Botnet

As seen in the above image, a bot herder initiates the attack by infecting several devices with malicious code, which acts as the Botnet. In the next step, these devices take over and conduct the final cyber attack. Therefore, even if you trace the cyberattack back in such a scenario, you cannot trace the bot herder easily.

In the next segment of this tutorial on what is a botnet, you will dive deeper into understanding botnets and look at the architecture of a botnet. 

Botnet Architecture 

A botnet architecture has developed over a while for improved working and slimmer chances of getting traced. As seen previously, once it infects the desired number of devices, the botmaster (bot herder) takes control of the bots using two different approaches.

• Client-Server Model

Fig: Client-server model

The client-server model is a traditional model that operates with the help of a command and control (C&C) server and communication protocols like IRC. For example, IRC or Internet Relay Chat sends automated commands to the infected bot devices. 

Before engaging in a cyberattack, it frequently programs the bots to remain dormant and await commands from the C&C server. When the bot herder issues a command to the server, it is then relayed to the clients. Following this, the clients run the commands and report back to the bot herder with the findings.

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• The P2P Botnet

Fig: Peer-to-Peer Network 

Instead of using C&C servers, we have the P2P approach. Here, controlling infected bots involves a peer-to-peer network that relies on a decentralized approach. As seen in the above image, bots are topologically interconnected and act as both C&C servers and clients. Today, hackers adopt this approach to avoid detection and single-point failure. 

In the P2P botnet approach, the infected devices scan for malicious websites or other devices. The bot carefully probes random IP addresses until it comes in contact with another infected machine. The bots then share updated commands or the latest versions of the malware. 

The next part of this tutorial on what is a botnet will acquaint you with the famous botnets of all time.  

Famous Botnet Attacks

Now that you have understood how a botnet works, you can imagine how dangerous it can be. The networks of enslaved devices are behind various dangerous cyber attacks. You will now look at a few sophisticated botnets.

• Mirai

Mirai is one of the famous botnets associated with IoT devices. First found in 2016, it primarily targets online consumer devices and has been used in some of the most disruptive DDoS attacks.

• Mariposa

Emerged in 2009, the Mariposa botnet committed online scams and launch DDoS assaults. It was also stealing personal account credentials from victims so that its operators could sell them on the Dark Web.

• Zeus

This financial Trojan accounted for 90% of all global online bank fraud instances at their peak. Emerging in July 2007, it was used to steal data from the United States Department of Transportation.

• Storm

First identified in 200, Storm was one of the first P2P botnets with a massive network ranging from 250,000 to 1 million infected devices. The Storm handled attacks from DDoS to identify theft.

• 3ve

First discovered in 2016, 3ve was a different type of Botnet that did not steal data or money and instead generated fake clicks on online advertisements hosted by fake websites.

Those were a few of the destructive and dangerous botnets in history. So, heading to the next section of this tutorial on what is a botnet, you will learn how to protect yourself from a botnet attack.

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How to Protect Yourself From Botnets

You require an all-inclusive strategy ranging from good surfing habits to software updates to anti-virus protection to prevent botnet infection. Listed below are some essential methods to keep botnets away.

1. Updating your operating system is a good malware preventative measure.
2. Beware of phishing emails and avoid email attachments from suspicious sources.
3. Refrain from clicking on suspicious links and be careful about which site you use for downloading information. 
4. Install anti-virus, anti-spyware, and firewalls on your systems.
5. If you are a website owner, establish a multi-factor verification method and implement DDoS protection tools. This will safeguard your website from botnet attacks.

Following these steps will help you guard your network and devices from hackers. This sums up this tutorial on what is a botnet.  

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Conclusion

In this tutorial on what is a botnet, you understood what a botnet is and how it works; you also learned its architecture. You had a look at the different types of botnets and how you can protect yourself from them. 

Cybersecurity is a booming field in today's times. If you are looking to learn ethical hacking to protect networks from cybercriminals. In that case, Simplilearn's Advanced Executive Program In Cyber Security will help you master advanced network packet analysis and penetration testing techniques to build your network security skill-set.

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