Botnet Attacks: How They Work and How to Stay Safe

Your computer, phone, or smart thermostat could be secretly working for a cybercriminal right now. Here is how botnets hijack devices and what you can do to stop them.

Your computer, phone, or even your smart thermostat could be working for a cybercriminal right now. You would never know it. That is the reality of botnet attacks. A botnet is a network of infected devices, all controlled remotely by an attacker. These hijacked machines, called “bots,” work together to carry out large-scale cybercrime. From crashing websites to stealing passwords, botnet attacks cause serious damage to individuals and businesses every single year. The worst part? Most victims have no idea their device is involved.

In this guide, you will learn how botnet attacks work, why they are growing more dangerous, and exactly how to protect yourself.

What Is a Botnet?

Think of a botnet as a robot army. Each “soldier” is a regular device, like your laptop, phone, or security camera, that has been secretly infected with malware. The person controlling this army is called a “bot herder.”

Once your device is infected, the bot herder can command it to do things without your knowledge. Your device still works normally on the surface. But in the background, it could be sending spam emails, helping crash websites, or mining cryptocurrency for the attacker.

The first botnets appeared in the late 1990s. They were small, maybe a few hundred computers used to send spam. Today, botnets can include millions of devices spread across the globe. The scale has changed dramatically, but the basic idea remains the same: hijack devices, build an army, and use it for profit.

How Botnet Attacks Work

These threats follow a predictable pattern with three stages. Understanding each step helps you spot the warning signs early and shut things down before real damage is done.

Stage 1: Infection

The bot herder first needs to get malware onto your device. This usually happens through phishing emails that trick you into clicking a malicious link, downloading infected software from untrusted websites, or exploiting security flaws in outdated software. Once the malware installs itself, your device quietly connects to a command and control (C&C) server. Think of the C&C server as the bot herder’s remote control panel.

Stage 2: Building the Network

One infected device is not very useful on its own. The bot herder uses each compromised device to spread the malware further, infecting more machines automatically. Over time, the botnet grows from dozens to thousands, or even millions, of connected bots. Each new device adds more firepower to the network.

Stage 3: The Attack

When the botnet is large enough, the bot herder issues commands through the C&C server. Common botnet attacks include:

• DDoS attacks: flooding a website with so much traffic that it crashes and goes offline
• Spam campaigns: sending millions of junk or phishing emails from your device
• Credential theft: logging your keystrokes to steal passwords and banking details
• Cryptocurrency mining: using your device’s processing power to mine crypto, which slows everything down
• Ransomware distribution: spreading ransomware to lock your files and demand payment

Why Botnet Attacks Are Getting More Dangerous

Botnets are not a new problem. They have been around for over two decades. But several trends are making modern botnets far more threatening than anything we have seen before.

Smart Devices Are Easy Targets

Your smart fridge, baby monitor, doorbell camera, and voice assistant all connect to the internet. Most of these IoT (Internet of Things) devices ship with weak default passwords and rarely receive security updates. Attackers love them.

In 2016, the Mirai botnet hijacked hundreds of thousands of IoT devices and launched one of the largest DDoS attacks ever recorded. Major websites like Twitter and Netflix went offline for hours. The devices used in the attack were mostly home routers and security cameras with factory-default passwords that their owners never changed.

AI Is Making Botnets Smarter

Attackers are now using artificial intelligence to build botnets that dodge detection. AI-powered bots can learn the behavioral patterns that antivirus software looks for, then adjust their activity to slip past those defenses. This makes modern botnet attacks much harder to catch with traditional security tools.

AI also helps bot herders automate the process of finding and exploiting vulnerable devices. What used to take weeks of manual work can now happen in minutes.

Botnets and Cryptocurrency

Cryptocurrency gives attackers a simple way to profit from botnet attacks. They can use your device’s processing power to mine crypto coins without your knowledge, a practice called “cryptojacking.” They can also use botnets to distribute ransomware and demand payment in hard-to-trace cryptocurrency. The anonymity of these digital currencies makes it extremely difficult for law enforcement to track down the attackers.

Cloud Resources as Weapons

Cloud computing gives bot herders access to massive processing power. Compromised cloud accounts can be used to host C&C servers, launch larger DDoS attacks, or store stolen data. Because cloud services scale automatically, a single compromised account can cause outsized damage.

How to Protect Yourself from Botnet Attacks

The good news is that protecting yourself does not require technical expertise. These straightforward steps make a real difference.

Keep Everything Updated

Software updates patch the security holes that bot herders exploit. Turn on automatic updates for your operating system, browser, and apps. This includes your router’s firmware, which many people forget about. Do not ignore those update notifications.

Use Strong, Unique Passwords

Change default passwords on every device, especially routers and smart home gadgets. Use a password manager to create and store strong, unique passwords for each device and account. If a service offers two-factor authentication, turn it on.

Install Reputable Security Software

Good antivirus software can detect and block botnet malware before it infects your device. Keep it running and updated. Many free security tools offer solid protection for individuals and small businesses.

Be Careful What You Click

Most botnet infections start with a phishing email or a malicious download. If an email looks suspicious, do not click the links. Download software only from official sources. When in doubt, go directly to the company’s website instead of clicking a link in an email.

Secure Your Home Network

Change your router’s default admin password. Enable WPA3 encryption if your router supports it. Consider setting up a separate network for IoT devices so that a compromised smart bulb cannot reach your laptop or phone.

The Cybersecurity and Infrastructure Security Agency (CISA) recommends regularly reviewing which devices are connected to your home network and removing any you no longer use.

Signs Your Device Might Be Part of a Botnet

How do you know if your device has already been recruited? Botnet malware is designed to stay hidden, but there are warning signs you can watch for:

• Your device runs unusually slow, even after restarting
• Your internet connection is sluggish without explanation
• Your data usage or electric bill spikes unexpectedly
• Your antivirus software gets disabled without your input
• You notice unfamiliar programs running in the background

If you spot these signs, run a full malware scan immediately. If the scan finds something, change all your passwords from a separate, clean device. You can also check whether your email has appeared in known data breaches at Have I Been Pwned.