A single compromised device can open the door to a full-scale cyberattack—and for businesses, that door is often wider than they think. Botnet attacks use networks of infected devices to launch powerful, coordinated assaults that can cripple websites, steal sensitive data, or silently siphon resources for criminal gain. These attacks are not only growing in frequency but also in sophistication, targeting everything from enterprise servers to everyday IoT devices. For any organization that depends on digital infrastructure, understanding how botnets work and how to stop them is vital to maintaining security, continuity, and customer trust.

Understand Bot and Botnet

What is a Bot?

A bot is an automated software application programmed to carry out specific tasks online with speed and precision. While bots can be used for legitimate purposes like indexing websites or answering customer queries, they can also be exploited for malicious activities. In cybersecurity contexts, malicious bots might be used to scan for vulnerabilities, harvest data, or attempt login credentials across thousands of sites. These programs function independently and are capable of performing repetitive tasks far more efficiently than a human.

What is a Botnet?

A botnet is a network of devices that have been secretly infected with malware and brought under the remote control of a cybercriminal, often referred to as a bot herder. These compromised devices, which may include computers, phones, or IoT products, are typically unaware of their role in the network. Once part of the botnet, these “zombie” devices can be coordinated to launch large-scale cyberattacks, such as flooding a server with traffic or distributing malware. Botnets pose a serious threat because of their scale, automation, and the difficulty in detecting and shutting them down.

Key Differences and Uses between Bot and Botnet

• Structure: A bot is a single automated agent, while a botnet is a coordinated group of many bots working together under one controller.
• Control: Bots may act on their own or as part of a system, but in a botnet, each device operates under centralized remote control.
• Purpose: Bots can serve both legitimate and malicious purposes. Botnets are almost always malicious, used for attacks like DDoS, mass spamming, data breaches, and distributing ransomware.
• Use Cases:
• Bots: Website indexing, chat automation, credential stuffing, data scraping.
• Botnets: Launching cyberattacks at scale, spreading malware, generating fake traffic, mining cryptocurrency illicitly.

What is a Botnet Attack?

A botnet attack is a type of cyberattack that involves a network of internet-connected devices infected with malware and controlled remotely by a hacker. These compromised devices, often called zombie bots, are used to carry out coordinated malicious actions. The most common form of botnet attack is a Distributed Denial of Service (DDoS) attack, where the attacker floods a target with excessive traffic to disrupt its normal functioning. Botnets can also be used to send spam emails, mine cryptocurrency for financial gain, steal sensitive user information through spyware, spread ransomware, and generate fraudulent web traffic. Any internet-connected device, such as computers, mobile phones, smart home gadgets, or security cameras, can become part of a botnet if not properly secured.

How Botnet Attacks Work?

Botnet attacks involve a network of compromised devices, known as "zombie bots," controlled by a malicious actor called a bot herder. These attacks are orchestrated to execute various cyberattacks, such as data theft, spam distribution, or distributed denial-of-service (DDoS) attacks. Botnets can be built from scratch by the bot herder or rented as Malware-as-a-Service (MaaS) from dark web marketplaces. The infected devices are managed through either a centralized client-server model or a decentralized peer-to-peer (P2P) model.

Botnet Control Models

• Centralized Client-Server Model

In this model, a single server acts as the primary C&C hub, issuing commands to all zombie bots. Proxy or sub-herding servers may be used to relay instructions, but all directives originate from the central server. This approach is simpler to set up but vulnerable, as targeting and disabling the central server can disrupt the entire botnet. As a result, centralized botnets are considered less resilient and are becoming less common.

• Decentralized Peer-to-Peer (P2P) Model

In a P2P botnet, control is distributed across all infected devices, with each bot capable of relaying commands to others. This structure eliminates reliance on a single server, making it significantly harder to detect or dismantle. The decentralized nature obscures the identity of the bot herder, as commands can propagate through any compromised device. P2P botnets are more sophisticated and prevalent due to their resilience and anonymity.

Three Common Stages of a Botnet Attack

Botnet attacks progress through three critical stages: Vulnerability Identification, Device Infection, and Botnet Mobilization. Each stage is strategically designed to maximize the botnet’s reach and impact while evading detection.

Stage 1: Vulnerability Identification & Exploitation

Botnet attacks begin with hackers scouring for weaknesses in software, human behavior, or IoT devices, such as unpatched systems, reused passwords, or even a lapse in user behavior like clicking suspicious links. to create entry points for malware, aiming to expose devices to infection without arousing suspicion.

Stage 2: Device Infection & Malware Injection

Once a path is identified, the attacker proceeds to infect devices. This stage relies on various malware delivery techniques, including phishing emails, drive-by downloads from compromised websites, or direct exploits of unpatched system flaws, as seen in the TrickBot botnet’s use of malicious Excel files to infect devices. When the victim unknowingly activates the payload—often disguised as legitimate software—their device is silently recruited into the botnet. The infection typically uses stealth tactics like polymorphic code to evade antivirus detection, allowing attackers to maintain persistence across many endpoints.

Stage 3: Botnet Mobilization & Control

After infiltrating multiple systems, the attacker assembles the infected devices into a coordinated network controlled from a central server or through a peer-to-peer (P2P) model. This network(now a botnet) can be directed remotely to execute large-scale attacks. Common objectives include launching DDoS attacks, as demonstrated by the 2016 Mirai botnet’s 1.2 Tbps attack on DynDNS, sending spam, mining cryptocurrency, ransomware campaigns like WannaCry in 2017, which locked 200,000+ systems, or spreading the infection further. The more devices that are added, the more powerful and damaging the botnet becomes.

Common Types of Botnet Attacks

Below are the most common types of botnet attacks, each designed to achieve specific malicious objectives.

• Distributed Denial-of-Service (DDoS) Attacks: Botnets flood a target server, website, or network with excessive traffic, such as HTTP, SYN, or UDP floods, to disrupt accessibility. Each zombie bot sends numerous requests, causing service outages, financial losses, and reputational damage.
• Data Theft: Botnets steal sensitive information, like login credentials or financial details, using malware such as keyloggers or spyware. Data is transmitted to the bot herder via command-and-control (C&C) servers, leading to identity theft, financial fraud, or unauthorized system access.
• Spam and Phishing Campaigns: Botnets send mass emails, SMS, or social media messages containing malicious links or attachments to spread spam, scams, or phishing attempts. This results in malware propagation, financial scams, and further botnet expansion.
• Credential Stuffing and Brute Force Attacks: Botnets perform automated login attempts using stolen or generated credentials to gain unauthorized access to accounts. This leads to compromised accounts, unauthorized transactions, and potential escalation to broader network attacks.
• Cryptojacking: Botnets hijack infected devices’ processing power to mine cryptocurrencies using covert mining scripts. This causes reduced device performance, higher energy costs, and financial gains for the attacker.
• Malware Distribution: Botnets deliver additional malware, such as ransomware or trojans, through email attachments, malicious links, or network vulnerabilities. This expands the botnet and compounds damage from secondary infections.

Signs of Botnet Infections

• Unusual Network Activity: Devices may exhibit high outbound traffic, especially to unknown or suspicious IP addresses, indicating communication with command-and-control (C&C) servers. Slow internet speeds or unexpected data usage spikes are common red flags.
• System Performance Issues: Infected devices often experience sluggish performance, frequent crashes, or high CPU/GPU usage due to malware activities like cryptojacking or sending spam.
• Suspicious Processes or Files: Unfamiliar applications, processes, or files running in the background, particularly those with random or obfuscated names, may indicate malware presence.
• Unauthorized Account Activity: Unexpected login attempts, password changes, or unusual activity in user accounts can result from credential theft or brute force attacks facilitated by botnets.
• Increased Spam or Phishing: If a device is sending out spam emails, SMS, or social media messages without user knowledge, it may be part of a botnet’s spam or phishing campaign.

How to Stop and Prevent Botnet Attacks in 2025?

Preventing Botnet attacks demands a multifaceted approach, combining proactive security measures, advanced detection, and user awareness to block infections and mitigate risks. Below are 6 key strategies to safeguard yourself and your business from botnet attacks.

1. Prioritize Immediate Software Updates

Ensure all operating systems, applications, and firmware are updated immediately upon release. Cybercriminals exploit known vulnerabilities in outdated software to infiltrate systems and recruit devices into botnets. Enable automatic updates where possible, and if manual updates are necessary, schedule them weekly to patch security gaps swiftly. Delayed updates leave systems exposed to attacks targeting publicly disclosed weaknesses.

2. Implement AI-Driven Botnet Detection

GeeTest offers a next-generation bot management solution to combat evolving botnet threats, leveraging unsupervised machine learning and behavioral biometrics to analyze trillions of data points daily, identifying botnet activity in real time. Its adaptive algorithms detect anomalies in user interactions (e.g., mouse movements, session patterns) and block malicious traffic before it reaches servers. Additionally, GeeTest continuously monitors network traffic, detecting unusual patterns like data leaks or Distributed Denial-of-Service (DDoS) attack spikes by tracking flow and volume, establishing baselines, and triggering alerts for anomalies, enabling early mitigation. With minimal setup, GeeTest automatically filters untrusted bots while allowing legitimate traffic, ensuring seamless protection without manual intervention.

3. Enforce Strict Password Policies

Require complex, unique passwords for all accounts, particularly administrative and internet-facing systems. Use password managers to simplify compliance and eliminate reuse. Integrate multi-factor authentication (MFA) to add an extra layer of defense against credential-stuffing attacks, which botnets often deploy to breach accounts. Regularly audit passwords and revoke access for unused or compromised credentials.

4. Deploy Advanced Anti-Malware Defenses

Invest in anti-malware software with real-time scanning to block botnet-related infections. Ensure the solution updates automatically to recognize emerging threats and performs scheduled deep scans to uncover hidden malware. Combine this with network segmentation to isolate infected devices, preventing botnets from spreading laterally across your infrastructure.

5. Implement Zero Trust Architecture

Unlike traditional perimeter-based security, a zero trust model assumes threats exist within the network, requiring continuous verification of every user, device, and application. By enforcing “never trust, always verify” principles, zero trust minimizes the risk of botnet malware spreading laterally, ensuring robust protection in 2025’s threat landscape.

6. Educate Users to Counter Phishing

Phishing via email, SMS, or social media is a primary method for spreading botnet malware, making user education critical. Training users to verify sender identities, avoid unexpected links or attachments, manually enter URLs, and use antivirus software to scan content prevents initial infections, breaking the cycle of botnet propagation through social engineering.

Conclusion

Botnet attacks represent a formidable challenge in today’s interconnected digital landscape, capable of crippling businesses, stealing sensitive data, and eroding customer trust. While no defense is entirely foolproof, proactive measures can significantly reduce risks. For robust, real-time protection, specialized tools like GeeTest offer advanced bot detection capabilities, identifying and neutralizing malicious traffic before it infiltrates your infrastructure.

Remember: cybersecurity is a continuous race against innovation. Investing in adaptive defenses and fostering a culture of cyber-awareness ensures you’re not just reacting to threats, but staying steps ahead of them.