What Is a Botnet? Understanding Botnet Attacks and DDOS threats

Introduction

Botnets quietly infect thousands or even millions of devices, turning them into remote-controlled weapons that can launch devastating attacks. From overwhelming websites with traffic to stealing sensitive information, botnets play a central role in modern cybercrime.

This blog explains what a botnet is, how botnet attacks work, the role of botnets in DDoS attacks, and a real-world example: the Meris DDoS botnet. You’ll also understand the risks, warning signs, and answers to common questions about botnet attacks.

What Is a Botnet?

A botnet is a network of internet-connected devices that have been infected with malicious software and are controlled remotely by a cybercriminal, often referred to as a botmaster or attacker. Each infected device is known as a bot or zombie, and the device owner is usually unaware their system has been compromised.

Botnets can include a wide range of devices such as computers, smartphones, servers, routers, webcams, and other Internet of Things (IoT) devices. Once infected, these devices follow commands sent from a central control system or decentralized communication structure without the user’s consent.

The primary strength of a botnet lies in numbers. While a single infected device may cause limited harm, thousands of them acting together can cripple websites, networks, and even entire online services.

What Is a Botnet Attack?

A botnet attack occurs when a cybercriminal uses a botnet to carry out malicious activities at scale. Instead of attacking from one machine, the attacker leverages hundreds or millions of infected devices simultaneously, making the attack harder to detect, block, or trace.

Botnet attacks can target individuals, businesses, governments, or critical infrastructure. Because traffic originates from legitimate devices across different locations, security systems often struggle to distinguish malicious activity from real user behavior.

Common botnet attacks include spam campaigns, credential stuffing, malware distribution, cryptomining, and distributed denial-of-service (DDoS) attacks. These attacks are often automated, persistent, and financially motivated.

Botnet Attack Statistics

Massive Increase in Botnet-Driven DDoS Attacks

• In March 2025, there were more than 27,000 botnet-driven DDoS attacks, averaging about 880 attack events per day with peaks over 1,600 attacks in a single day.
  
• In July 2025, researchers observed over 20,000 botnet-driven DDoS events more than 600 per day with spikes above 1,100 on certain days.
  
• Overall DDoS activity in 2025 is extremely high, with some reports estimating millions of DDoS attempts globally, driven largely by automated botnets.
  

Growth in Botnet Size

• A massive botnet detected in Q1 2025 consisted of 1.33 million infected devices, nearly 6× larger than the biggest botnet seen in 2024.
  
• By Q2 2025, the same botnet grew to approximately 4.6 million unique IPs blocked during mitigation around 20× larger than 2024 records.
  
• In Q3 2025, this botnet continued to expand, with mitigation systems blocking 5.76 million IP addresses tied to botnet traffic.
  

DDoS Attack Frequency and Trends

• Recent industry reports highlight that botnet-driven attacks dominate overall DDoS activity, rising in sophistication and frequency.
  
• Some sources indicate botnets account for a significant share of global DDoS traffic, causing disruptions across IT, finance, e-commerce, media, and communications sectors.

How does Botnet DDoS Attack work?

Following is the detail how process unfolds. 

1. Attacker

The process starts with the attacker, who plans and initiates the DDoS attack. The attacker does not directly interact with the target. Instead, they control the attack remotely to hide their identity and location.

2. Bot Coordinator (Command-and-Control Server)

The attacker sends instructions to a bot coordinator, also known as a Command-and-Control (C&C) server. This server acts as the central communication hub, managing all infected devices and issuing attack commands such as start time, target IP address, attack type, and duration.

3. Botnet (Infected Devices)

The botnet consists of thousands or even millions of compromised devices such as computers, servers, routers, and IoT devices. These devices are infected with malware and remain under the attacker’s control without the owners’ knowledge.

Once the bot coordinator sends the command, all bots activate simultaneously and begin generating malicious traffic toward the target.

4. Victim (Target System)

The victim is usually a website, server, application, or network infrastructure. As the botnet floods the victim with massive traffic requests at the same time, the system becomes overwhelmed.

Due to limited bandwidth and server resources, the victim system slows down, crashes, or becomes completely unavailable to legitimate users successfully causing a Distributed Denial of Service (DDoS).

Types of Botnet Attacks

Botnets are used to carry out a wide range of cyberattacks, depending on the attacker’s objective. Once devices are compromised and added to a botnet, they can be remotely instructed to perform malicious activities at scale. The most common types of botnet attacks are explained below.

1. Distributed Denial of Service (DDoS) Attacks

DDoS attacks are the most well-known type of botnet attack. In this attack, the botnet floods a target website, server, or network with massive amounts of traffic at the same time. The goal is to overwhelm system resources so legitimate users cannot access the service. These attacks often result in downtime, revenue loss, and reputational damage.

2. Spam Email Attacks

Botnets are widely used to send large volumes of spam emails. Each infected device sends spam messages, making the campaign difficult to trace or block. These emails often contain phishing links, malware attachments, or fraudulent offers designed to steal personal or financial information.

3. Phishing and Credential Theft

In this type of attack, botnets help distribute phishing content at scale. Victims are tricked into entering usernames, passwords, or banking details on fake websites. Some botnets also include keylogging capabilities that directly capture credentials from infected devices.

4. Malware Distribution

Botnets are often used to spread additional malware. Compromised devices can be instructed to download and install new malicious software, such as ransomware, spyware, or trojans. This allows attackers to expand their botnet or launch new attacks without direct interaction.

5. Data Theft and Surveillance

Some botnets are designed specifically to steal sensitive data. These botnets can monitor user activity, capture keystrokes, take screenshots, or access stored files. Stolen data may include login credentials, personal information, business data, or financial records.

6. Click Fraud Attacks

In click fraud attacks, botnets generate fake clicks on online advertisements. This drains advertising budgets and falsely inflates traffic metrics. Businesses running pay-per-click (PPC) campaigns are common victims, while attackers earn revenue from fraudulent ad interactions.

7. Cryptomining Attacks

Botnets can hijack the computing power of infected devices to mine cryptocurrencies without the owner’s consent. This results in slow system performance, higher electricity usage, and potential hardware damage, while attackers profit from the mining activity.

8. Brute Force and Credential Stuffing Attacks

Botnets are used to perform large-scale brute force attacks by trying many password combinations across multiple accounts. In credential stuffing attacks, stolen username-password pairs are tested on various platforms to gain unauthorized access.

9. Proxy and Anonymity Attacks

Some botnets turn infected devices into proxy servers. Attackers route malicious traffic through these devices to hide their real identity and location. This technique is often used to bypass geo-restrictions, security filters, or law enforcement tracking.

10. IoT-Based Botnet Attacks

IoT botnets specifically target smart devices such as cameras, routers, and smart appliances. These devices often have weak security settings, making them easy to compromise. IoT botnets are commonly used for massive DDoS attacks due to their large numbers.

Understanding Botnet DDoS Attacks in Detail

Botnet DDoS attacks are especially dangerous because they are distributed. Unlike traditional attacks from a single source, traffic in a botnet DDoS attack comes from many geographic locations and IP addresses. This makes it difficult for security teams to block malicious traffic without also blocking legitimate users.

Attackers can also change tactics mid-attack, switching between different types of DDoS methods such as volumetric floods, protocol attacks, or application-layer attacks. This flexibility allows botnets to bypass basic security defenses and prolong downtime.

In many cases, botnet DDoS attacks are used for extortion. Attackers may threaten organizations with ongoing disruptions unless a ransom is paid, often in cryptocurrency.

Meris DDoS Botnet: A Real-World Example

The Meris DDoS botnet is one of the most powerful botnets ever observed. It gained attention for launching some of the largest DDoS attacks in history, generating traffic volumes measured in tens of millions of requests per second.

Unlike many botnets that rely on malware-infected computers, Meris primarily exploited misconfigured or vulnerable network devices, especially routers. These devices were hijacked and used to send massive amounts of legitimate-looking traffic, making detection extremely challenging.

Meris attacks demonstrated how dangerous botnets can be when they exploit weaknesses in internet infrastructure. Even well-protected organizations with advanced security systems were affected, highlighting the evolving sophistication of botnet-driven DDoS attacks.

How Botnets Are Created and Controlled?

Botnets are typically created by exploiting security vulnerabilities, weak passwords, or outdated software. Once malware gains access to a device, it installs a small program that allows the attacker to control it remotely.

Control can be centralized, where all bots communicate with a command-and-control (C&C) server, or decentralized, using peer-to-peer communication. Modern botnets often use encryption and stealth techniques to avoid detection and takedown.

Attackers continuously update botnets by adding new infected devices, replacing bots that are cleaned, and adapting malware to evade security solutions.

Why Botnet Attacks Are So Effective?

Botnet attacks succeed because they rely on scale, automation, and anonymity. The use of legitimate devices makes traffic appear normal, while global distribution complicates attribution and blocking.

Many botnets exploit everyday devices that lack strong security, such as IoT products. Users often forget to update firmware or change default passwords, unintentionally contributing to botnet growth.

Additionally, botnets are relatively cheap to operate compared to the damage they cause, making them an attractive tool for cybercriminals.

How Botnet Attacks Can Be Prevented?

Preventing botnet attacks requires a combination of good cybersecurity practices, proactive monitoring, and strong network defenses. Since botnets rely on infected devices and weak security, reducing vulnerabilities is the most effective way to stop them.

1. Keep Systems and Software Updated

Regularly updating operating systems, applications, and firmware helps close security vulnerabilities that botnets exploit. Many botnet infections occur because devices are running outdated software with known flaws.

2. Use Strong and Unique Passwords

Weak or default passwords make devices easy targets for botnet malware. Using strong, unique passwords for routers, IoT devices, and online accounts significantly reduces the risk of unauthorized access.

3. Install Reliable Security Software

Antivirus and anti-malware solutions can detect and remove botnet-related malware before it spreads. Keeping security software updated ensures protection against newly emerging botnet threats.

4. Secure IoT Devices

IoT devices are common botnet targets due to poor security settings. Change default credentials, disable unnecessary features, and update device firmware regularly to prevent them from being hijacked.

5. Monitor Network Traffic

Unusual spikes in traffic, unexplained data transfers, or abnormal device behavior may indicate botnet activity. Continuous network monitoring helps detect infections early and limit damage.

6. Use Firewalls and Intrusion Detection Systems

Firewalls block unauthorized access, while intrusion detection and prevention systems (IDS/IPS) identify suspicious behavior. These tools help stop botnet communication with command-and-control servers.

7. Educate Users About Cyber Threats

Phishing emails and malicious links are common infection methods. Training users to recognize suspicious emails, attachments, and websites reduces the chances of devices becoming part of a botnet.

8. Implement DDoS Protection Services

For organizations, DDoS mitigation services and content delivery networks (CDNs) help absorb and filter malicious traffic. These solutions ensure services remain available during botnet-powered attacks.

9. Segment Networks

Network segmentation limits the spread of malware. If one device becomes infected, segmentation prevents the botnet from easily accessing other systems within the same network.

10. Regular Security Audits and Patch Management

Conducting routine security audits helps identify weaknesses before attackers exploit them. Timely patch management ensures vulnerabilities are addressed quickly.

Conclusion

Botnets are one of the most serious and persistent threats in today’s digital landscape. By silently hijacking everyday devices, attackers can launch large-scale botnet attacks, including devastating DDoS campaigns like those carried out by the Meris botnet. These attacks highlight the importance of strong cybersecurity practices for both individuals and organizations.

Understanding how botnets work, how devices become infected, and what risks they pose is the first step toward prevention. Regular updates, strong passwords, and proactive security measures can significantly reduce the chances of becoming part of a botnet and help keep the internet safer for everyone.

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