In recent years, botnets have become increasingly sophisticated. Nowadays, botnets can launch massive DDoS attacks, steal data from infected computers, and even infect new computers with malware.

If you run a website, email server, or any type of online service, then you should be concerned about being attacked by a botnet. This guide will teach you how to protect against these types of attacks.

What is a Botnet Attack?

A botnet attack is a type of cyber attack carried out by a group of internet-connected devices controlled by a malicious actor. Botnets themselves are simply a network of devices. It is when cyber criminals inject malware into the network to control them as a collective that they get used for launching cyber attacks. Botnet attacks can be used for sending spam, stealing sensitive information, compromising confidential info, perpetuating ad fraud, or launching more dangerous Distributed Denial of Service or DDoS attacks.

Bot Attacks vs a Botnet Attack

Botnet attacks can be considered a specific type of the more general “bot attack”. Bot attacks are cyber attacks that use automated web requests meant to tamper with a website, application, or device.

Bot attacks initially consisted of simple spamming operations but have evolved to be more complex in nature, intended to defraud or manipulate users. One reason is the availability of open-source tools for building bots, known as botkits. These botkits, usually available for free online or on the Dark Web, can be used to carry out nefarious tasks like scraping a website, taking over an account, abusing form submissions, and creating botnet attacks, including DDoS attacks.

How Does a Botnet Attack Work?

Botnet attacks start with cyber criminals gaining access to devices by compromising their security. They could do this via hacks like the injection of Trojan horse viruses or basic social engineering tactics. Then these devices are brought under control using malicious software that commands the devices to carry out attacks on a large scale.

Sometimes, the criminals themselves may not use the botnet to launch attacks, but instead, they sell access to the network to other threat actors. These third parties can then use the botnet as a “zombie” network for their own needs, like directing spam campaigns.

The Different Types of Botnets

Botnet attacks can differ based on their methods and tools. Sometimes these botnets don’t attack but instead become a pathway for hackers to launch secondary campaigns like scams and ransomware attacks. Some common types of attacks include:

• Distributed Denial-of-Service (DDoS) attacks: One of the more common types of botnet attacks which work by overloading a server with web traffic sent by bots to crash it. This downtime in the server’s operation can also be used for launching additional botnet-based attacks.
• Phishing attacks: Often launched with the goal of extracting key information from an organization’s employees. For instance, mass email spam campaigns can be designed to imitate trusted sources within the organization to trick people into revealing confidential information like login details, financial info, and credit card details.
• Brute force attacks: These involve programs that forcefully breach web accounts. Dictionary attacks and credential stuffing are used to exploit weak user passwords and access their data.

What Systems & Devices are Most at Risk?

When cybercrimes such as botnet attacks make the news, the damages are usually shown as the number of computers or servers compromised. But it’s not just individual systems that can be infected. Any device connected to the internet is vulnerable to botnet attacks.

With the growth of the Internet of Things (IoT), more devices than ever are online, increasing attack vector possibilities. Even seemingly harmless wireless CCTV cameras can be compromised to open an entry point for botnet malware. The issue is worsened when these IoT devices have poorly configured security settings.

Detecting Botnet Attacks

Botnet attacks are hard to detect because the user is often unaware when a device is compromised. Some botnets are designed with a central server controlling each bot in a command-and-control model. Detecting attacks for these botnets involves finding that central server.

Static analysis techniques can help spot infected machines. These are run when the device is not executing any programs and involve looking for malware signatures and suspicious connections to command-and-control servers.

Behavioral or dynamic analyses can also be used if there are more resources. These involve scanning ports on local networks and looking for unusual traffic and activity involving Internet Relay Chat (IRC).

Antivirus software can detect botnet attacks to a certain extent but fails to spot infected devices. Another method is using honeypots, fake systems that bait a botnet attack via a fake infiltration opportunity.

For larger botnets, like the Mirai botnet, ISPs might work together to detect traffic flow and figure out how to stop the botnet attack by identifying compromised devices in the network.

Can Botnet Attacks be Prevented?

Preventing botnet attacks is challenging, particularly with the proliferation of devices, each with different security settings. However, some measures can still help:

• Keep all systems updated: Botnets exploit unpatched vulnerabilities, so it is critical to keep systems updated and install new updates quickly. This includes hardware, especially legacy devices which might be ignored.

• Adopt basic cybersecurity best practices: Use complex passwords and educate employees about phishing and suspicious attachments. Ensure new devices in networks have robust security settings.

• Control access to machines: Use multi-factor authentication, limit access to critical systems, and ensure that access is controlled and separated.

• Monitor network traffic using analytics solutions: Use advanced analytics to monitor traffic flows, user access, and data leaks to prevent attacks like the Mirai botnet.

How to Mitigate Against Botnet Attacks

Despite prevention efforts, botnet attacks can still occur. Mitigation focuses on reducing the impact:

• Disable the central server: For command-and-control model botnets, disable the server to take down the botnet.

• Run antivirus or reset the device: For compromised individual computers, use antivirus, reinstall software, or reformat the system. For IoT devices, flash the firmware or perform a factory reset.

Botnet Attack FAQs

Why Do Hackers Use Botnets?

Hackers use botnets to attack numerous computers simultaneously. Botnets, networks of compromised computers remotely controlled, can send spam, steal data, or perform other malicious activities.

What’s the Difference Between a DoS Attack and Botnet Attack?

A denial of service (DoS) attack disrupts access to a website by flooding it with requests. A botnet is a network of computers used for these attacks, aiming to control computers to launch DoS attacks against others.

What’s a Bot Herder?

Bot herders are hackers who take over vulnerable computers to use as botnets. They install malware to control devices for attack purposes, sometimes renting their network to other cybercriminals.