What are botnets?

What are botnets? Types of botnets and their impact on cybersecurity

What are botnets, and why are they considered a major cybersecurity threat? A botnet is a network of internet-connected devices that have been infected with malware, leading to a malware infection. These devices are controlled remotely by cybercriminals without the knowledge of the owner. The infected devices are often referred to as “bots” or “zombies.”

Botnets are used to carry out various cyberattacks. These include sending spam emails, launching Distributed Denial of Service (DDoS) attacks, stealing sensitive data, and more. Because of their scale and hidden nature, botnets are one of the most dangerous tools in the hands of cybercriminals today. Learn more about how DDoS attacks work and how they can disrupt systems and services.

What is a botnet?

A botnet is a group of compromised devices that are under the control of a cybercriminal, also known as a bot herder. The hacker uses malicious software to infect the devices and connects them to a central command and control (C&C) system. Once part of the botnet, each device follows the instructions sent by the attacker.

While botnets can perform legitimate tasks, they are often misused for malicious purposes, such as launching cyberattacks and stealing data.

Botnets can consist of many types of devices, including personal computers, mobile phones, servers, and Internet of Things (IoT) devices such as smart cameras or home assistants. Explore how the growing number of IoT devices expands the cyber attack surface and increases vulnerability.

Botnet architecture

A botnet’s architecture refers to the design and structure of the network, including the relationships between the infected machines and the control servers. There are two primary models of botnet architecture: the client-server model and the peer-to-peer (P2P) model.

Client-server model

The client-server model is a centralized architecture where a single control server, also known as the command and control (C&C) server, controls and coordinates the actions of the infected machines. The C&C server sends commands to the infected machines, which then execute the commands and report back to the server. This model is often used for botnet attacks such as DDoS attacks, where a large number of infected machines are needed to overwhelm a target system. The client-server model is also used for botnet malware distribution, where the C&C server distributes malicious software to the infected machines.

Peer-to-peer (P2P) model

The P2P model is a decentralized architecture where each infected machine acts as both a client and a server. In this model, each infected machine communicates with other infected machines directly, without the need for a central control server. The P2P model is often used for botnet operations that require a high degree of autonomy and flexibility, such as ad fraud and phishing campaigns. The P2P model is also more difficult to disrupt than the client-server model, as there is no single point of failure.

How botnets are created

Botnets are created through a process of infection and recruitment, where vulnerable devices are infected with malicious software and then recruited into the botnet. The process typically involves the following steps:

1. Infection: A device is infected with malicious software, such as a Trojan horse malware, through a variety of means, including phishing attacks, drive-by downloads, and exploitation of vulnerabilities. Learn more about how Trojan malware works and how to protect your device.

2. Recruitment: The infected device is recruited into the botnet by the bot herder, who uses the device to communicate with other infected devices and coordinate their actions.

3. Control: The bot herder establishes control over the infected device, using it to execute commands and carry out malicious activities.

Common types of botnets

Centralized botnets

In a centralized botnet, all bots connect to one main command server. This setup allows the attacker to manage the botnet efficiently. However, it also creates a single point of failure. If the server is shut down, the entire botnet can be disabled.

Peer-to-peer (P2P) botnets

Peer-to-peer botnets have no central command server. Instead, each bot communicates with other bots in the network. This structure makes them harder to detect and shut down, but also more difficult to control and manage.

Zombie botnets

Zombie botnets are networks of infected devices that operate silently in the background. These devices perform tasks like sending spam or participating in DDoS attacks without the user’s knowledge. Zombie botnets are among the most common in the world.

Social media botnets

Some botnets use social media platforms for communication and control. They spread quickly by exploiting trusted networks, and they are often used for phishing, spreading misinformation, or stealing personal data.

Mobile botnets

With the growing number of smartphones and tablets, mobile botnets have become increasingly common. These botnets target mobile operating systems to steal data, send premium text messages, or track user activity.

How do botnets work?

Botnets generally follow three main steps:

1. Infection: Devices become infected through phishing emails, malicious websites, or software downloads, leading to a botnet infection. Once infected, a device becomes part of the botnet.

2. Connection: The infected device connects to the command and control system. This can be either centralized or decentralized, depending on the botnet type.

3. Execution: The botmaster sends instructions to the infected devices. These can involve launching cyberattacks, harvesting data, or spreading malware further.

What is a botnet attack?

A botnet attack is when the attacker uses the network of infected devices to carry out harmful activities. These attacks can target individuals, businesses, or entire infrastructures. Common examples include:

• Overloading websites or servers with traffic

• Sending out mass spam or phishing campaigns

• Stealing login credentials and personal information

• Clicking on ads to commit ad fraud

• Using brute force attacks to breach web accounts and gain unauthorized access

Because botnets can include thousands or even millions of devices, the attacker has access to massive computing power and can operate at a global scale.

Types of botnet attacks

There are several types of botnet attacks, including:

1. DDoS attacks: A DDoS attack is a type of botnet attack where a large number of infected machines are used to overwhelm a target system, making it unavailable to legitimate users.

2. Malware distribution: Botnets are often used to distribute malicious software, such as viruses, Trojans, and spyware, to vulnerable devices.

3. Ad fraud: Botnets are used to commit ad fraud, where false web traffic is generated to deceive advertisers and generate revenue.

4. Phishing campaigns: Botnets are used to conduct phishing campaigns, where infected machines are used to send spam emails and steal sensitive information from victims.

5. Exploitation of weak user passwords: Botnets are used to exploit weak user passwords, using automated tools to guess or crack passwords and gain unauthorized access to systems.

These types of botnet attacks can have significant consequences, including financial loss, reputational damage, and compromised sensitive information. To prevent botnet attacks, it is essential to implement robust security measures, such as antivirus software, firewalls, and intrusion detection systems, and to educate users about the risks of botnets and how to avoid them. Additionally, law enforcement agencies and cybersecurity professionals must work together to disrupt and dismantle botnet operations, and to bring bot herders to justice.

Why are botnets a cybersecurity risk?

Botnets are difficult to detect because the infected devices often continue to work normally from the user’s perspective. However, in the background, they may be sending out data, executing attacks, or generating malicious traffic. Their ability to operate silently and scale rapidly makes them a serious threat to both individuals and organizations.

How to prevent botnet infections

Technical measures

• Install reputable antivirus and anti-malware software

• Use firewalls and intrusion detection systems

• Regularly update software and operating systems to patch vulnerabilities

• Ensure that internet infrastructure hardware, such as routers and web servers, are secured and regularly updated

Behavioral practices

• Avoid clicking on suspicious links or downloading unknown files

• Be cautious with email attachments and pop-ups

• Only install apps and software from trusted sources

How to detect and stop botnets

Monitor network traffic

Unusual network activity can indicate the presence of a botnet or malicious code. Security teams should monitor for patterns such as unexpected data transfers or repeated connections to unknown IP addresses.

Block malicious IPs

If certain IP addresses are found to be part of a botnet, they can be blocked to prevent further communication with infected devices.

Use security tools

Dedicated software can help detect and remove malware associated with botnets. Regular scans and updates increase the chances of identifying and stopping threats before they spread.

Isolate infected devices

If a device is compromised, disconnect it from the network immediately. Perform a full malware scan and apply necessary updates before reconnecting it.

Final thoughts on botnets

Understanding what botnets are and how they work is essential in today’s digital landscape. Whether you’re a private user or part of an organization, awareness and proactive cybersecurity practices can help prevent botnet infections and reduce the impact of potential attacks.

Frequently asked questions

Are botnets illegal?

Yes. In most countries, creating, operating, or using botnets is illegal because it involves unauthorized access and control of other people’s devices.

How do I know if my device is part of a botnet?

Common signs include slow performance, unusual network traffic, and unauthorized logins. Running a malware scan with updated antivirus software is a good first step.

Why do cybercriminals use botnets?

Cyber criminals use botnets for anonymity, automation, and massive scale. They can be used for financial gain, data theft, corporate espionage, or service disruption. Cyber criminals leverage botnets to steal passwords, launch attacks on unsuspecting devices, and enhance their reputation within the hacking community by showcasing their capabilities to infect and control numerous computers.