A botnet refers to a network of devices that are infected by a malware, allowing them to be controlled by a hacker. The hacker, known as the bot herder, usually controls the network of bots through a command centre.
Devices become part of a botnet when they are infected with a particular malware. Such malware infections are usually spread through phishing links, spam mails, and unofficial software downloads from the internet.
It’s hard to tell if your device is part of a botnet. But unexplainable reduction in processing power, slower internet connection speeds, and unfamiliar programs and files usually indicate the presence of botnet malware.
Detecting and removing botnet malware can be challenging even for cybersecurity experts. Hence, it’s best to prevent an infection in the first place. Installing an antivirus scanner, like Norton 360, is the best way of preventing a botnet malware infection.
The rest of the article explains how botnets works and provides more tips on how you can prevent a botnet infection.
A botnet is a collection of devices connected to the internet and controlled by hackers, often unbeknownst to the user. Hackers infect these devices with malware allowing them to control them and use them for different purposes, such as DDoS and spam attacks. In May 2023, cybersecurity firm Imperva revealed that “bad bots” are becoming more sophisticated and harder to detect.
But how do hackers build a botnet? What are some of the signs of a botnet infection? How can you protect your devices? We answer all these questions and more in this article.
What is a Botnet?
The term ‘botnet’ is a combination of two words: Robot and network. Robot here refers to an infected computing device, which could be a computer, mobile device, smart TV, or other similar internet of things (IoT) devices. Network refers to the collective group of infected machines controlled by the hacker.
The hacker controlling the botnet is often referred to as the bot herder or bot master. The bot master is the central point that controls the actions of the entire network and can use it to cause severe harm to the infected devices and other devices. Bot herders who control larger botnets can cause significant damage to critical internet infrastructure used by the Government and large organizations.
What can a botnet do?
Botnet malware grants a range of permissions and authorizations to the hacker, allowing them to control the whole device virtually. However, hackers will usually only use some of the device’s processing capability to avoid detection. Some of the specific actions a Botnet can perform on an infected device are:
- Installing applications and malware, such as keyloggers
- Moving, copying, or deleting files
- Gathering and transferring sensitive user data
- Scanning for other devices on common or shared networks
- Diverting the device’s computing power for combined DDoS or spam attacks
What are the different kinds of botnets?
Botnets are usually classified on the kind of architecture they use. There are two major kinds of architecture, namely: centralized and decentralized. Each of them works in the following manner:
Centralized botnets
In a centralized botnet architecture, each bot or infected device is connected to a common command and control server. The server is usually controlled by a hacker or cybercriminal, who uses it to achieve their objectives, such as DDoS or spam attacks.
The simple hierarchy and structure of a centralized botnet, also known as the “client-server model,” cause it to be more efficient. The bot herder only needs to change or update the command and control server to alter the functionality of the entire botnet. In other words, the bot herder can quickly change the botnet from one that primarily carries out DDoS attacks to one that gathers financial information.
However, a major downside of the centralized botnet architecture is its single point of failure. If the common command and control server is inoperative, the entire botnet ceases to exist.
Decentralized botnets
To resolve the single point of failure problem associated with centralized botnets, hackers now use decentralized botnets. In such an architecture, each infected device acts as both the node and a command and control server.
You can also think of it as a peer-to-peer botnet model. Each peer has the entire control structure embedded inside it. Hence, there is no need for a centralized command server.
While decentralized botnets are tougher to take down, they can be taken over by anyone controlling more than 50% of active bots as there is no single command center.
How is a botnet created?
The steps involved in creating a botnet can be broken down as follows:
- Device and vulnerability identification. The hacker or cybercriminal must first identify the device or set of devices they would like to include in their botnet. IoT devices are an increasingly popular choice for botnets as they often lack sophisticated security protocols.
- Malware placement. Once the hacker has identified the target device, they will try and deliver a package containing the botnet malware to the device. There are various ways to do this. One of the most popular forms is by using phishing links or fake websites that contain trojan horse programs. Alternatively, hackers can exploit existing device vulnerabilities, such as zero-day exploits, to install the malware.
- Installation. The botnet malware must be installed on the target device before the hacker can control it. Installation can sometimes rely on the user executing the file. In other instances, it can self-execute and replicate itself across the device.
- Connection and activation. The malware installed on the target device will communicate with a command and control server, usually operated by the hacker. This server is used to deliver instructions to the botnet on the future course of action.
What are Botnets Used For?: Types of Botnet Attacks
Botnets are well suited to long hacking campaigns that require the sustained and continuous use of computing power. Additionally, they are ideal for targeted attacks against pre-identified institutions and organizations. Some of the more common uses of Botnets are listed below:
1. DDoS attacks
The most common use of a botnet is for conducting DDoS attacks. The term “DDoS” refers to distributed denial-of-service. This means that too many devices try to access a website at the same time, which crashes the site’s servers, resulting in a failure of service. Such a DDoS attack can cause a website to be unreachable to real users. Botnets can also be used to launch brute-force attacks.
2. Spam and phishing
Without the owners of the devices knowing, they can be used to spread spam or phishing emails and messages. The bot master can send emails to individuals in your contact list or post on Facebook under your name. Your friends and family might open these emails or click on links because they trust you. Without knowing it, you might infect everybody around you with bots or other viruses and spyware.
3. Sell credentials
Once a hacker has placed a bot on your device, they gain access to all the information on it. This means they probably know your passwords and login information. As a result, they can steal your identity and do things in your name. Moreover, they might sell this information to others using the dark web.
4. Bitcoin mining
To mine bitcoin, you need a lot of processor power. The bot herder can use the processor power of the bot-infected devices to mine bitcoin. This happens without the owners of the devices knowing. However, it is questionable whether or not this mining method is actually worthwhile because you need a lot of bots to generate a small sum of money.
5. Malware infection and spreading
Botnets can be potent tools to distribute malware, particularly ransomware, to other connected devices. The hacker instructs the bots to detect vulnerabilities in other devices and drop the malware files using common network infrastructure. Resultantly, botnets can be used to quickly infect a large number of devices with a certain kind of malware.
Famous Examples of Botnet Attacks
It’s always easier to grasp a concept when linked to real-world examples. The following table provides some examples of famous botnet attacks in history.
| Name of Botnet | Year | Description |
|---|---|---|
| EarthLink Spammer | 2000 | EarthLink Spammer is the first recorded instance of a botnet attack. Khan Smith used the spam botnet to send emails to unsuspecting users in the hopes of attaining their financial credentials. |
| Mariposa | 2008 | A Spanish botnet aimed at stealing credit card numbers, Mariposa included nearly 10 million devices at its peak. This makes it one of the largest botnets ever discovered. The robot network was brought down by Spanish law enforcement who were able to detect the perpetrators behind it. |
| Necurs Botnet | 2012 | Necurs is a massive botnet that infected close to nine million computers globally. It was used to spread spam and dangerous malware, including the notorious GameOver Zeus banking trojan. The Necurs botnet was successfully disrupted by Microsoft and partner agencies in 2020. |
| Hong Kong Attack | 2014 | Two pro-democracy Hong Kong websites were repeatedly targeted by DDoS attacks in June 2014. It is widely believed that the “Hong Kong” DDOS attack used a botnet to inundate the pro-democracy websites. There’s also some speculation that the Chinese Government was behind the attack, though this has not been confirmed |
| Mirai Botnet | 2016 | Mirai is one of the most famous botnet attacks. It specifically targeted smart devices of IoT devices running on ARC processors. While the original creators of Mirai have been caught, its source code lives on and has been used to launch massive DDoS attacks over the years. |
| Glupteba Botnet | 2019-current | Glupteba is a new kind of botnet that uses blockchain architecture to spread. It primarily targets Windows devices to mine cryptocurrencies and steals user credentials. Google disrupted the Glupteba in 2021, but it has since resurfaced, pointing to the resilience that blockchain-based architecture brings. |
Am I Part of a Botnet?: Possible Signs of a Botnet Infection
Botnets are increasingly sophisticated and the average user probably won’t even know if their devices are part of one. Hackers and cybercriminals intentionally use only a portion of a device’s computing power to avoid detection. However, there are some tell-tale signs of a botnet infection:
- Reduction in processing speeds. Botnets use some processing power to fulfill their objectives. As a result, you may see noticeable drops in your device’s performance. You can also visit your device’s Task Manager or Activity Manager to see which applications and services are using processing capacity.
- Frequent app crashes. If you notice apps or programs frequently crashing on your device, it could result from reduced processing capacity caused by a botnet.
- Slower internet speeds. A botnet programmed to send spam emails, launch phishing attacks, or detect other network devices will use up your internet bandwidth. So, if your internet speeds are inexplicably slower than before, your device may be part of a botnet.
- Unauthorized social media posts and emails. Bot herders increase their network by making fake social media posts or sending emails to your contact list. An uptick in unfamiliar posts or emails from your accounts is a telltale sign of a botnet infection.
- Unfamiliar files and applications. A botnet can sometimes install additional files and programs to further its spread or install malicious software on your devices. It could point toward a botnet infection if you notice new and suspicious files or programs you haven’t downloaded or installed. However, this is a relatively common symptom of other malware infections, such as ransomware.
What to Do If Your Device is Infected by Botnet Malware
If you’re experiencing some of the symptoms above, it’s quite likely that your device has a botnet malware infection. In such a situation, you must focus on isolating the infected device and then identifying and removing the malware. Here’s what you can do:
- Disconnect your device from any network. This involves disconnecting your device from your WiFi and disabling any Bluetooth connections. It is vital to take this step to prevent other devices from being infected.
- Identify the malware. You can do this through an antivirus scanner, such as Norton 360. Alternatively, you can manually search for any suspicious files. However, the latter method can be quite painstaking and slow. Moreover, there’s a chance of identifying the wrong file, including system files that are crucial to your device functioning properly.
- Remove the malware. This can also be done either automatically or manually. The automatic route is preferable as it ensures the infectious files are completely removed from your device. If you want to remove the files manually, we’d recommend doing so in Safe Mode to prevent any unintended consequences.
- Reset your device. In case you continue to experience symptoms of a botnet malware infection after taking the above steps, it may be necessary to reset your device and reinstall your operating system. If you must restore previous files, it’s advisable to use a backup before the symptoms of a botnet infection showed up.
- Report the botnet infection to the relevant authority. While you’ve removed the botnet malware infection from your device, the botnet still exists and remains active. To prevent further harm to others, you should report the infection to the relevant cybersecurity authorities. For US residents, this would be the Cybersecurity and Infrastructure Security Agency.
How to Prevent a Botnet Attack
Botnet malware detection is not straightforward. Hence, your best option is to prevent a botnet infection in the first place. The steps outlined below should help prevent botnet infections and improve your device’s overall security.
Avoid clicking on suspicious links
Botnets, like most forms of malware, are primarily spread through phishing links and spam mail. By avoiding unfamiliar links, you can reduce the chances of downloading botnet malware onto your devices.
In addition to unfamiliar links, you should also avoid downloading any mail attachments from senders you do not recognize. Such attachments are another common way to spread botnet malware.
Do not download programs or software from unverified sources
While downloading free software from the internet can seem like a great deal, it’s important to remember that there’s probably a good reason the software is free. Usually, the reason is that the free software file includes malware, such as a botnet.
Of course, there are several websites that offer legitimate free software downloads and are secure. Using these isn’t usually a problem. However, it’s best to exercise abundant caution and have a firewall running on your device. This will prevent downloads of files that are infected with malware, including botnet malware.
Change default password settings on your smart devices
Most IoT devices have a default username and password. These default passwords are fairly easy to guess and make your devices an easy target for hackers. To avoid your smart devices becoming part of a botnet, change the default password to a more secure one.
A secure password is usually a combination of characters, numbers, and alphabets. It should also be between 10 and 16 letters long. Generating such secure passwords can be quite a challenge. However, with a password manager, you can generate countless such passwords and store them securely. This way, you never have to worry about forgetting long and complex passwords.
Keep your IoT devices on a separate Wi-Fi network
Since IoT devices are relatively easy targets for botnet hackers, you can prevent the infection from spreading by keeping IoT devices on a different WiFi network. You can do this by either creating a separate band on your router or by buying a new secure VPN router.
Another good safety practice is to set up a guest network on your WiFi router. This will ensure that infections from devices belonging to people visiting your office or house do not spread to your devices.
Regularly update your operating system and other software.
IT and software companies regularly release patches and updates that resolve security issues in their software or hardware. Keeping your devices updated can help ward off potential botnet attacks.
Install an antivirus scanner
An antivirus scanner is essential to ensure the security of your devices. It scans your devices for potential malware and removes them before they can infect your device. Additionally, leading antivirus scanners like Norton 360 feature a firewall, which prevents infected files from being downloaded on your device.
Norton 360 comes with a 100% virus protection promise. This means that if a Norton expert cannot remove a virus from your device, including a botnet, you will be eligible for a refund. It also features a password manager which, as mentioned previously, can help keep your devices secure from possible botnet infections.
Conclusion: Protect Your Device Against Botnets
Botnet malware is particularly dangerous as it can infect and run on your devices for a considerable period of time without detection. Additionally, it can infect other network devices and include them within the larger botnet. Devices infected by a botnet can suffer in terms of performance and connectivity.
Since botnets are difficult to detect, it’s advisable to adopt a multi-prong prevention strategy. Such a strategy should center around an antivirus scanner, like Norton 360, that detects and deletes any botnet malware on your devices. In addition to installing an antivirus scanner, you should follow basic but important digital safety practices, such as avoiding suspicious links and not downloading software from unverified sources.
While botnets can be particularly dangerous, they are just one form of malware that can infect your devices. Read some of our other articles to learn more about the different kinds of malware that can affect your devices:
- What is Remote Access Trojan? Remove and prevent RATs.
- What is Spyware? How Do You Protect Your Devices?
- Killware: What is it and How Can You Protect Yourself?
Most readers probably several questions about what Botnets are and how they function. We’ve answered some of the most common questions related to Botnets below
A botnet refers to a collection of devices that are controlled by a hacker or group of hackers. The hackers infect target devices with malware that allows them to remotely control the device.
Once a device is infected and included in the botnet, it can be used to complete a range of objectives. These include launching DDoS attacks, sending spam mails, infecting other devices etc. Refer to our article on botnets for a deeper understanding of what they are they can do.
A botnet is usually created by infecting devices with malware that allows hackers and cybercriminals to control them remotely. The malware is typically spread vis phishing links or spam mails. Alternatively, hackers can also exploit device vulnerabilities to install the malware.
Devices that are part of a botnet can also be used to be infect other devices and increase the size of the botnet.
In terms of infected devices and financial loss caused, ZeUS is probably the largest botnet. It infected closet to 130 million devices at its peak and lead to a financial impact of at least $120 million. The largest botnet in terms of cumulative computing power in Mantis, which launched a 26 million requests per minute DDoS attack.
A botnet is not illegal in and of itself. In some cases, botnets can be used to harness idle computing space on devices in a productive manner. However, where the device is included in a botnet without the owner’s knowledge and is used for illegal purposes, it would also be illegal.
