What is a Botnet?

Botnets are networks of compromised internet-connected devices (also referred to as bots or zombies) infected with malware that are remotely managed by hackers/cybercriminals and managed through Trojan or fake software update websites.Understanding how botnets operate is vital to taking practical preventive steps to safeguard both your home and business.

Botnets are networks of computers and devices infected with malware that allow a hacker to remotely control them for malicious use, such as spamming or conducting Distributed Denial of Service [DDoS] attacks. Botnets may also be rented out to cybercriminals.

Bot malware typically comes in Trojan horses or can spread through security vulnerabilities like web browser holes like worms. Once an unwary user opens one of these Trojan horses, modules that enable remote attackers to command and control it are installed onto the device and use this information against its owners.

An attacker can wait until enough infected devices have joined a botnet before sending instructions to attack specific servers, for instance, flooding them with traffic. Bots also monitor user activity, including keyloggers that record keystrokes to steal sensitive information or gain entry to banking websites.

Older bots were quickly taken down, while newer versions relying on peer-to-peer networks or other management channels for transmitting commands between bots can make them harder to spot and shut down.

Signs of botnet infection include:

Definition of a Botnet

Botnets are networks of computers and devices infected with malware and remotely controlled by attackers to send spam, launch Distributed Denial of Service attacks, and steal data. Botnet devices may belong to their attackers or be rented out to other cybercriminals for malicious use.Attackers gain control of botnets through deceptive means, usually by convincing victims to install malicious software - usually Trojan horse programs which install modules into victims' computers that join an illicit network. This may happen through drive-by downloads, exploiting browser vulnerabilities, or via emails with attachments inviting victims to install more malware - once installed; it will typically stay silent until given commands by its operator.

Botnets can be used for multiple purposes. They often launch DDoS attacks against servers and networks, steal passwords and sensitive information, send spam mail out, and potentially even hijack point-of-sale [PoS] systems for various criminal acts.

Disrupting a botnet requires cutting off command and control (C&C) servers. Historically, this was achieved by targeting IRC networks or domains, but as botnet malware has evolved, so have its disruption methods. Hackers use peer-to-peer networks and other management channels more frequently to keep their botnets operational even after being shut down by law enforcement or security vendors.

Protection against botnets comes in various forms, such as prohibiting particular third-party code from running on your device and employing advanced protection systems that monitor for malware in incoming and outgoing data packets. Egress filtering examines outgoing streams to prevent dangerous software from leaving the network.

Types of Botnets

Hackers use botnets to steal user data, take over systems, launch DDoS attacks, and engage in illicit activities. They do this by infecting thousands or millions of devices with malware and connecting these Internet-connected objects to a massive network. These devices may include computers, laptops, tablets, mobile phones, routers, or other technologies used to enable and support Internet connections. As attacks become increasingly sophisticated, attackers target Internet of Things (IoT) devices like home automation and security products. These include smart light bulbs, TVs, cameras, network routers, and devices like glucose monitors and pacemakers.

Once a device has been infected with bot software, it begins communicating with a server acting as the bot herder's control center and receiving orders to join or control a botnet. These orders could include anything from DDoS attacks, spam-sending and crypto mining operations, and downloading more malware.

Law enforcement authorities find this model easy to detect and shut down; thus, hackers have turned to more decentralized approaches, such as peer-to-peer botnets that communicate over the Internet to spread instructions.

Hackers use botnets to launch large-scale malicious campaigns that would otherwise be too expensive or difficult to manage on their own, such as DDoS attacks that require infecting hundreds of thousands or millions of devices or phishing campaigns that breach an enterprise database to obtain customer or employee data.

Botnet Structures

Malware infections often take control of devices to carry out malicious tasks, like redirecting clicks on online advertisements to generate revenue for hackers. Another malicious botnet widely used in 2017 was Zeus malware which attacked thousands of devices simultaneously while stealing user data.

Initial botnets were constructed using a client-server model in which infected computers directly responded to a central server for direction and commands, making this model easily detectable by cybersecurity vendors and law enforcement agencies. Recently however, cybercriminals have developed more advanced decentralized botnets by embedding their command-and-control (C&C) software within the existing peer-to-peer file-sharing networks - this makes the resulting bots harder to detect as each bot is simultaneously both client and server.

Notably, some bots can be programmed to self-proliferate and expand their network without needing a C&C server for guidance. Instead, these bots connect with other infected devices on a P2P botnet to share preconfigured commands, thus escaping detection by security products and teams or being shut down by devices in their network.

An infection might begin with something as basic as a Trojan horse or exploit kit, but its goal is ultimately to create an entire network of zombie devices that hackers can remotely manage. A botnet could infiltrate any device with access to an Internet connection - from traditional desktop and laptop computers and laptops through smartphones, tablets, smart televisions, and gaming consoles - including Black Friday computer sales where hackers would buy hundreds of computers using credit cards maxed out for this purpose.

Botmasters

Hackers who administer botnets are known as bot-herders or botmasters, responsible for infecting computers with malicious code that transforms them into mindless "bots" that carry out the hacker's commands - often designed to crash networks, harvest credentials or perform CPU-intensive tasks such as CPU mining. Bot herders typically rent out access to these "bots" on the black market for considerable financial gain.

Hackers use various techniques to infiltrate computers. One tactic involves persuading victims into performing drive-by downloads or exploiting web browser vulnerabilities with Trojan horse programs that install modules allowing their botnet to communicate back with attackers via IRC channels and other communication protocols - this practice is commonly called home.

Once a bot is active, it can execute malicious functions or send information back to its "herder," who then can use this data to resell or repurpose them for criminal activities such as spamming, phishing, and DDoS attacks.

Bots can spread to other devices through self-spreading functionality, which listens for commands from their "bot-herder." This attack, commonly called "worming" or "exploiting," exposed vulnerable systems to all cyber threats, including email spam, click fraud, and ad fraud attacks.

Bitdefende EDR