What is a Botnet Attack? Signs Your Device is Already Infected

Your device can join this criminal network without any visible signs. No pop-ups. No crashes. No obvious malware warnings. Botnets are designed to hide in plain sight, silently turning millions of innocent devices into weapons of mass digital destruction.

According to Cloudflare, 71% of HTTP DDoS attacks in Q2 2025 were initiated by known botnets.

Understanding how botnet attacks actually work and the surprisingly simple steps to detect and prevent them could be the difference between being a victim and staying protected. Keep reading, because what you’re about to discover will change how you think about every device in your home forever.

What Is a Botnet?

A botnet is a network of infected computers, known as bots, that are under the control of a hacker. These bots are usually regular PCs and devices that have been compromised by malware and are now remotely controlled. The hacker uses the collective power and resources of the botnet to carry out cybercrimes like:

• Distributing spam and malware
• Launching DDoS attacks to take down websites
• Stealing personal data and account information

Once your device is infected with botnet malware, it can be difficult to remove. The hacker works hard to keep their botnet secret so they can utilize your resources without you even realizing it.

The truth is botnet attacks have become incredibly common. Some estimates show over 30% of all PCs connected to the internet are part of a botnet. These malicious networks are responsible for over 80% of all spam and a large portion of DDoS assaults.

How Does a Botnet Attack Work?

• The “bot herder,” also known as the “bot master,” controls the botnet using command and control (C&C) software. 
• The bot herder sends commands to the bots, instructing them to carry out malicious activities like distributed denial-of-service (DDoS) attacks, spam email campaigns, bitcoin mining, and data theft.
• Because botnets consist of many devices scattered around the world, they can be difficult to detect and disrupt. 
• The bot herder will often use anonymizing techniques to hide their identity and location.
• As technology and security practices evolve, bot herders are constantly adapting their methods to avoid detection and continue manipulating their botnets.

The scary truth is botnet attacks have become extremely common. Once infected, your device can become a pawn used to harm others at any time.

Types of Botnet

Botnet attacks come in a few common forms. Each uses a network of infected computers under the control of the attacker:

Distributed Denial of Service (DDoS)

A DDoS attack floods a target website with traffic from the botnet, overloading it and taking it offline. The attacker controls the botnet to direct a massive amount of requests at the site simultaneously, more than it can handle.

Spam Campaigns

The botnet can also be used to send massive amounts of unsolicited spam emails. The spam is generated on the infected computers in the botnet and sent through their internet connections, hiding the true source.

Bitcoin Mining

Some botnets are used to mine Bitcoin and other cryptocurrencies. The combined computing power of the botnet is harnessed to solve the complex equations required for mining digital coins. The profits go to the botnet operator rather than the computers’ owners.

Surveillance

In some cases, botnets are used to gather information on the people using the infected devices. Everything from keylogging to accessing webcams and microphones is possible, allowing the botnet operator to spy on victims.

As you can see, botnets pose a serious threat with a variety of malicious uses. The fact that attackers can gain control of thousands or even millions of devices should be alarming and highlights the importance of cybersecurity. With vigilance and proper precautions, you can reduce your risk of becoming part of a botnet.

The Rising Botnet Threat: How common are Botnet Attacks?

Botnet attacks are on the rise for several reasons. As more devices become connected to the Internet of Things (IoT), cybercriminals have more targets to infect and form into botnets. It’s estimated that by 2020, over 20 billion devices will be connected to the IoT, ranging from smart TVs and security cameras to routers and DVRs. Many of these devices have poor default security, making them easy prey for hackers.

Growth of Ransomware and Cryptojacking

Two of the most common payloads distributed by botnets are ransomware and cryptojacking code. Ransomware encrypts files and holds them for ransom, while cryptojackers secretly use your device’s computing power to mine cryptocurrency. As these types of cybercrime have become more lucrative, criminal organizations have invested heavily in developing stealthy botnets to spread them.

Some of the largest known botnets, like Mirai and Trickbot, now have millions of infected devices under their control. They are rented out or sold to the highest bidder, enabling massive attacks that are difficult to mitigate. A single Mirai attack in 2016 took down major websites like Twitter, Netflix, and PayPal.

With botnets only continuing to expand in size and sophistication, individuals and organizations must take proactive steps to secure their connected devices. Using strong, unique passwords, enabling two-factor authentication when available, and keeping software up to date are some of the best ways you can help reduce the threat of becoming part of a botnet. Together, we can work to curb the growth of these dangerous cyber weapons and make the Internet a safer place.

Real-World Examples of Devastating Botnet Attacks

Botnet attacks are more common than you might realize. Here are a few well-known examples of the damage they can cause:

Aisuru (2025)

It comprised hundreds of thousands of compromised IoT devices, dramatically surpassing Mirai’s size. It launched multi‑layered DDoS attacks, including randomized UDP floods and stealth HTTP request manipulations to evade defenses. It was notably used to campaign against KrebsOnSecurity with a 6.3 Tbps volumetric attack in May 2025.

Ballista Botnet (2025)

It exploited CVE‑2023‑1389 in unpatched TP‑Link Archer routers, infecting over 6,000 devices worldwide in early 2025. It was associated with an Italian threat actor; impacted sectors include healthcare, manufacturing, and tech across Australia, China, the U.S., Mexico, Poland, and the UK. It enables remote code execution, encrypted communication, data exfiltration, and DDoS potential.

Microsoft 365 Credential Attack (2025)

A botnet of around 130,000 compromised devices carried out password‑spraying attacks against Microsoft 365 accounts worldwide in April 2025. Attackers exploited legacy Basic Authentication to bypass Multi‑Factor Authentication, targeting non‑interactive sign‑ins. Microsoft plans to deprecate Basic Auth by September 2025.

Mirai (2016)

The Mirai botnet infected Internet of Things (IoT) devices like routers, webcams, and DVRs. At its peak, it compromised over 600,000 IoT devices. The botnet was used to conduct massive distributed denial-of-service (DDoS) attacks, including one against DNS provider Dyn that disrupted major websites like Twitter, Reddit, and Spotify.

Conficker (2008)

This worm targeted vulnerabilities in Windows to spread to millions of computers worldwide. It allowed cybercriminals to steal personal data, distribute malware, and conduct DDoS attacks. At the height of the infection, Conficker had compromised over 9 million Windows PCs.

As these examples show, botnet attacks pose a serious threat. They are often used to steal data, spread malware, send spam, or disrupt internet services. The massive scale of some botnets means that when they activate, the results can be catastrophic.

How to protect yourself and your Business from Botnet Attacks?

To protect yourself and your business from botnet attacks, there are a few key steps you should take:

Use strong, unique passwords

Use complex passwords that are different for each account. Long, random passwords with a minimum of 12 characters are best. Enable two-factor authentication whenever possible.

Be cautious of phishing emails

Never click links or download attachments from unsolicited emails. Phishing emails are a common way for botnets to infect devices. Delete suspicious emails right away.

Keep your software up to date

Install updates for your operating systems and software as soon as they become available. Updates often contain security patches to prevent vulnerabilities that botnets target.

Use reputable antivirus software

Antivirus software, especially those with built-in firewalls and malware detection, can help prevent botnet infections. Run regular scans to check for any infections.

Educate your employees

Train employees on cybersecurity best practices like spotting phishing emails, using strong passwords, and keeping systems up to date. Employees are frequently targeted, so education is key.

Monitor network activity

Watch for signs of botnet activity like unusual traffic, blocked IP addresses, or sudden spikes in bandwidth usage. These could indicate an active infection.

Backup critical data

Back up important files regularly in case of infection. Some botnets can lock access to files and demand ransom payment. Backups ensure you have unencrypted copies of your data.

Staying vigilant and taking proactive steps to strengthen your cyber defenses will reduce the risk of botnet attacks. But even with the best safeguards, infections can still happen. Monitor systems closely and take action quickly if an attack occurs.

Signs Your Computer Might Be Part of a Botnet

If your computer seems to be running slower than usual or you notice strange activity, it could be part of a botnet. Here are a few signs to watch out for:

Increased Spam or Pop-Ups

Botnets are often used to send spam, phishing emails, or launch popup ads. If you’re seeing a spike in unsolicited messages or annoying pop-ups, your device may have been compromised.

Higher Data Usage

Botnets frequently send and receive data to communicate with the command and control server. Check your internet data usage and see if there are any unexplained spikes. This could indicate your computer has been co-opted into a botnet.

Unexplained Processes Running

Botnets run hidden processes to carry out attacks without the user’s knowledge. Look for unfamiliar background processes running on your computer that are using CPU resources. End these processes immediately.

Connection to Unknown IP Addresses

Botnets connect to the control server to receive commands. Review your router or firewall logs to check for connections to unknown IP addresses. This is a telltale sign your computer has been roped into a botnet.

If any of these sound familiar, your computer could be part of a botnet. Run a reputable antivirus scan right away to check for infections. You should also change all passwords, enable two-factor authentication when available, and be on high alert for further signs of compromise. The sooner you take action, the less damage can be done. Staying vigilant and keeping your guard up is key to avoiding becoming prey for botnet operators.

How can AstrillVPN help in combating Botnet attacks?

AstrillVPN can help protect you from botnet attacks in several ways:

Encrypted Connection

AstrillVPN creates an encrypted tunnel between your device and the VPN server, hiding your online activity and location. This makes it much harder for botnet operators to infiltrate your system or steal your data. Even if their malware has infected your device, it will have a hard time communicating back to the botnet controller.

Secure Wi-Fi Protection

Public Wi-Fi networks are a prime target for botnet operators. Astrill VPN encryption prevents interception of your data by malicious actors, especially on public Wi-Fi, where botnets often scan for vulnerable devices. Also, AstrillVPN encrypts your connection even on unsecured networks by giving you access to perform VPN leak test, preventing hackers from accessing your data or planting malware on your device. You can connect with peace of mind from any hotspot.

Added Security Features

AstrillVPN includes additional features like an Internet kill switch, which cuts off all internet traffic if your VPN connection drops. This prevents your real IP and data from being exposed. AstrillVPN also offers malware and ad blocking for an added layer of protection.

FAQs

Botnets are malicious networks of infected devices controlled by hackers. Here are some common questions about these cyber threats:

Conclusion

These were the cold hard facts about botnet attacks. They’re more common than you probably realized and becoming more sophisticated each day. While the cybercriminals behind these attacks get smarter, the good news is you can outsmart them by taking some basic precautions. Staying vigilant and proactively protecting yourself online is the best defense against becoming part of a botnet. Take control of your cybersecurity and don’t become another pawn in their game.

Was this article helpful?

YesNo