Botnet

In this guide, you will discover what a botnet is, how it works, and how you can prevent your devices from being used in botnets.

What is a Botnet?

Created from the words “robot” and “network,” a botnet is a network of compromised devices at the will of a hacker. This network of robots becomes an “army” at the hands of a hacker because it can cause large-scale destruction. As a result, botnet attacks are more efficient to hackers when their “army” is as large as possible.

Hackers that control botnets are known as botmasters or bot herders.

Characteristics of a Botnet

• It is not easily detectable because the bot herder intentionally ensures that your computer continues operating normally to avoid alerting you.
• A botnet can stay dormant in devices for a long time waiting for the hacker to grow his army and eventually launch an attack.
• An advanced botnet is created in such a way that it can update itself to prevent detection by antivirus or antimalware software.

Hackers are constantly improving botnet designs to make them more difficult to find.

How Does a Botnet Work?

A botnet obtains access to your computer or other internet-connected devices through a piece of malicious coding, IoT hacking, a spider, or a Trojan horse.

A spider is a program that crawls the internet looking for security holes to exploit while a trojan horse is a type of malware that lures you to click a malicious link by disguising itself as a legitimate link. You can also infect your computer with a trojan by downloading malicious email attachments or software.

Once a botnet has gained access to your computer, it will contact the botmaster so that he or she can begin using your computer for malicious reasons.

Attackers use botnet structures to give them as much control as possible over the devices they compromise. The two botnet structures are as follows:

Client-server model

With this structure, the botmaster uses one main command and control (C&C) server to send instructions to each client device with the help of special software.

This structure is reliable in allowing the bot herder to control and maintain the botnet. However, this botnet is easy to bring down because law enforcement agents simply have to locate the C&C server and destroy it.

Peer-to-peer model

Instead of using a centralized C&C server, this structure uses the compromised devices as both the clients and servers. 

Each individual client will reach out to other infected devices to update and exchange information. As a result, a botnet using the P2P structure is more difficult to destroy.

Botnet Attacks

Also called a zombie army, a botnet is used to carry out a variety of attacks. Some of these attacks are listed below:

· Ad fraud

Bot herders create ad fraud schemes where they command thousands of compromised devices to go to fraudulent websites and click on ads. The attacker receives a percentage of the advertising money for every click.

· Spam distribution

A hacker can use infected computers to email spam to millions of internet users across the globe. Some organizations pay hackers to send out ads about their products via these spam emails.

Through spam distribution, hackers can infect more computers if owners download files attached to the spam email. Moreover, botmasters can send phishing emails to trick recipients to send their personal information.

· DDoS attacks

In a distributed-denial-of-service (DDoS) attack, a botmaster instructs infected computers to contact a website or server repeatedly. The sudden surge in traffic can overwhelm the website or server causing it to shut down.

Some botnets might use innocent computers to carry out a DDoS attack to stay hidden. To do this, the bot herder commands the infected computers to send connection requests to the innocent computers, also known as reflectors. When the reflectors receive these connection requests, it will appear as if they originated from the target website or server. The reflectors then send information to the website or server hence overloading it. The website or server then shuts down completely.

Once a botmaster has achieved his goals with a botnet, he can sell or rent it to other hackers for them to carry out other attacks.

Examples of real-world botnet attacks include Zeus, Methbot, and Mirai.

How to Protect Yourself

To keep your computer, phone, tablet, and home IoT devices from becoming part of a bot network, you should observe the measures below:

• Only download software and email attachments from trustworthy sources
• Secure your home Wi-Fi network
• Create strong and different passwords for all your devices
• Use security software to protect your devices from botnets
• Avoid downloading files from P2P networks
• Update the operating system of your devices regularly
• Do not browse the internet without a firewall
• Do not visit sites that distribute malware
• Enable two-factor authentication on your devices

For more topics on security threats, read what is a remote access trojan and how to protect yourself against it.