What is a Botnet?

The term “botnet” refers to a collection of computers linked together to perform a specific task. Botnets themselves are not a threat to your network. For example, some botnets perform helpful tasks like managing chatrooms or keeping track of points during an online game. However, when botnets are misused for malicious purposes, they can be very dangerous. This is because a botnet can control your computer and also use it to carry out attacks.

A botnet is a network of computers infected by malware that are under the control of a single attacking party, known as the “bot-herder.” Each individual machine under the control of the bot-herder is known as a bot.

Initially, botnets were created to make time-consuming tasks easier. An example was proctoring chatrooms and ejecting people who did things that went against the room’s policy, such as the use of inappropriate language. But because of a botnet’s ability to execute code inside another computer, people began to use them in the theft of passwords or to keep track of a user’s keystrokes. Botnets were then created to use other people’s computers to launch attacks against unsuspecting devices.

Botnets' popularity have been growing because they can be used for financial gain, attracting the efforts of greedy criminals. To gain the respect of others, cyber criminals use botnets to infect and control as many computers as they can. In this way, they construct a “resume” they use to show off their hacking skills.

There are several types of botnet attacks, and each has its own characteristics. The attacks use botmasters, zombie computers, spamming, spyware, click fraud, dial-up bots, and web crawling.

A botmaster refers to an individual that runs the C&C of botnets. They can execute the botnets’ functions remotely to launch distributed denial-of-service (DDoS) and other types of attacks. The botnets the botmaster uses are usually installed on computers using various types of remote code installation techniques. The botmaster conceals their identity using proxies, an Internet Protocol (IP) address, or The Onion Router (Tor) Project, which works in conjunction with the dark web.

The bots the botmaster deploys are set up to enable the C&C to manage them once a key or password is entered. When these keys get compromised, hackers can “hack” the botnets of their criminal competitors and then initiate DDoS attacks—and other types of attacks—of their own.

In a zombie attack, a computer that is connected to the internet is being controlled by a hacker or malware. The bot may be installed in the target computer using a Trojan horse. The computer becomes “mindless,” like a zombie, as the person or malware controls it, making it execute malicious tasks.

A spamming botnet, otherwise known as a spambot, refers to a machine that distributes spam emails to computers. These emails tend to have advertisements for products such as pornography, fake antivirus software, or counterfeit goods. The emails may also have computer viruses hidden within them.

Spammers may buy a botnet that has already infected many computers and then send out spam emails in an attempt to infect devices. With this method, it is harder to figure out where the attack originally came from.

A botnet hacker that uses spyware uses a botnet that can automatically click on links for online advertising or on webpages. Because these clicks often generate revenue for advertisers, spyware botnets can be used by enterprising criminals to earn a steady income.

Dial-up bots work by connecting to dial-up modems and forcing them to dial numbers. In this way, they can tie up a phone connection, which may force the user to switch numbers. In other cases, the botnet may call a premium phone number, which results in the target user getting a high phone bill. However, because dial-up modems are getting less and less common, these types of attacks are shrinking in popularity.

A web crawler, also known as a web spider, is a bot on a search engine that downloads and indexes website content. The objective of this kind of bot is to figure out what each website is about. In this way, that site can be matched to a searcher’s query when necessary. They “crawl” the web, grabbing information off websites, organizing, and categorizing it using software.

Avoiding botnets in the first place is a fairly simple process, especially if you know what to look for. Keep in mind that a botnet cannot do any damage if it cannot get inside your devices. In many cases, an unsuspecting user lets the botnet in by taking a specific action.

For example, a user may end up clicking on a link embedded in a message. Once the link is clicked, the botnet gains access to the user’s device. Avoiding these kinds of links can nip the problem in the bud.

Devices with weak security can be like a half-open door for botnets. Often, devices have default passwords that are easy to guess. Further, if a hacker has access to a list of default passwords that a device manufacturer tends to use, they may not have to do any deciphering at all. It is best to purchase devices with more advanced security features and then be meticulous about protecting each one with an adequately strong password or multi-factor authentication (MFA) system.

Email attachments put bots a click away from target devices. Anytime you get an email with an attachment, you should make sure the attachment is safe. Some email apps come with filtering capabilities that can scan attachments to verify their safety. 

When in doubt, if you think the attachment is necessary, it may be safer to open it in a sandboxed environment to prevent any bots from infecting your system. A sandbox keeps devices and areas of the network away from the rest of the system to limit and contain threats.

Treat every link within a message as suspicious. If the link is a tool of a botnet, it cannot harm your computer unless you click it. If you feel a link may contain vital information, you can right-click or long-press the link (depending on your device) to see where it leads without activating it.

Antivirus software, when properly configured, can be a powerful botnet deterrent. Many antivirus apps have been programmed with lists of botnets that may pose a danger to your system. They also update automatically, collecting the names and attributes of new botnets as they are detected.