What is a botnet?

A network of robots (botnet) refers to a group of computers that have been infected by malware and are under the control of a malicious agent. IP stresser The term botnet is a contraction of the words robot and "network," Each infected device is called a bot. Botnets can be designed to carry out illegal or malicious tasks, such as sending spam, stealing data, distributing ransomware, fraudulently clicking ads, or performing Distributed Denial of Service (DDoS) attacks.

While certain malware like ransomware directly affects the device owner, DDoS botnet malware can have different levels of visibility; thus, some malware is designed to completely take over the device, while others run silently as a background process waiting for instructions from the attacker or "bot herder."

Self-propagating botnets recruit other bots through several different channels. Infection routes include exploiting website vulnerabilities, Trojan horse malware, and decoding weak authentication to gain remote access. Once access is gained, all of these infection methods result in the installation of malware on the target device, allowing the botnet operator to achieve remote control. Once a device has been infected, it may attempt to self-propagate botnet malware by recruiting other hardware devices in the surrounding network.

While it is impossible to pinpoint the exact number of bots in a specific botnet, estimates for the total number of bots in a sophisticated botnet range from a few thousand to over a million.

Why are networks of robots (botnet) created?

The reasons for using botnets vary, from activism to disturbances financed by the states themselves. However, most attacks are aimed at obtaining financial gain. Hiring botnet services are relatively cheap, especially to the amount of damage they are capable of causing. There are also insufficient brakes or barriers to this activity, which makes some software developers decide to dedicate themselves to this lucrative business, especially in countries where regulations are lax or where these activities are not pursued. All this has led to the proliferation of online services offering attacks for hire.

How is a network of robots (botnet) controlled?

One of the main features of a botnet is receiving up-to-date instructions from the bot herder. The ability to communicate with every bot on the network allows the attacker to toggle attack vectors, change the target 

, end an attack, and other custom actions. Botnet designs vary, but control structures can be divided into two general categories:

The client/server botnet model

The client/server model mimics the workflow of a traditional remote workstation where each machine connects to a centralized server (or a small number of centralized servers) to access information. Each bot will join a command and control center (CnC) resource, such as a web domain or IRC channel, in this model to receive instructions. By using these centralized repositories to send new commands to the botnet, the attacker needs to modify the source material that each botnet consumes from a command center to update the instructions on the infected machines. . The centralized server that controls the botnet may be a device owned and operated by the attacker, or it may be an infected device.

Specific popular centralized botnet typologies have been observed, including the following:

Star network topology

Multi-server network topology

Hierarchical network topology

In this model (client/server), each bot connects to a command and control center, such as a web domain or an IRC channel, to receive instructions. By using such central repositories to send new commands to the network, the attacker has to modify the source material from which the botnet feeds to update the instructions of each infected device embedded in it.

Now, this simplicity of updating instructions (from a limited number of centralized sources) becomes the main vulnerability of the botnet: it is enough to intercept the central server to neutralize it. This has led to an evolution of this model and the emergence of new ones with fewer weak points.

The peer-to-peer botnet model

Thus, to solve this fragility of the client/server model, the most recent botnets incorporate a design based on decentralized peer-to-peer file sharing. Once integrated into a botnet, this type of control structure eliminates that weak point of a single control and command center, thus determining that neutralizing the botnet becomes more complicated. P2P bots can simultaneously be clients and command centers and work to spread data in collaboration with neighboring nodes.

P2P botnets are based on a list of trusted computers that can communicate (sending information to each other) and update malware. By limiting the number of devices each bot connects to, each bot is only exposed to adjacent devices, making tracking and mitigation difficult. On the other hand, by not having a single control center, these robot networks are more likely to become controlled by people other than their creators. But, to protect against this, these botnets are usually encrypted (thus limiting the possibilities of third-party access).

How do IoT devices become botnets?

No one does their online banking through the Wi-Fi camera they set up in the yard to watch the bird feeder, but that doesn't mean the device is incapable of making the necessary network requests. The power of IoT devices coupled with weak or poorly configured security creates a window for botnet malware to recruit new bots to the network. An increase in IoT devices has resulted in a new arena for DDoS attacks, as many devices are misconfigured and vulnerable.

When the vulnerability of an IoT device is written in the source code of its firmware, updates become more complicated. Any IoT device with older firmware should be updated to mitigate risk because the device's default credentials are often not changed. Many cheap hardware vendors lack incentives to make their devices more secure, leaving the described vulnerability as an unresolved security risk.

How do you disable an existing botnet?

Disable the control centers of a network of robots (botnet):

Botnets with a design based on a command and control center can be more easily disabled after detecting said center or centers. It is enough to neutralize these control centers (weak points) to bring down the entire network. For this reason, both system administrators and security forces focus on shutting down such control centers. However, the process is complicated when the command center is located in a country where legal or security force pressure is less.

Remove the infection from individual devices:

For individual computers, strategies to regain control of the machine include:

• Running antivirus software
• Reinstalling the software from a backup
• Starting over from a clean computer after reformatting the system

For IoT devices, strategies may include reinstalling (flash) the firmware, performing a factory reset, or otherwise formatting the device. If these options aren't feasible, the device manufacturer or a system administrator might offer other strategies.

How can you protect your devices from becoming robots in a botnet?

Create strong passwords:

For many vulnerable devices, reducing exposure to the botnet vulnerability can be as simple as changing the administrative credentials to something other than the default username and password. Creating a strong password makes brute force decryption difficult, so creating a solid password makes brute force decryption virtually impossible—for example, a device infected with the Mirai malware will scan IP addresses for responding devices. Once a device responds to a ping request, the bot will attempt to log in to that found device using a list of default credentials. Suppose the default password has been changed and a strong password has been implemented. In that case, the bot will give up and continue looking for other vulnerable devices.

Allow only trusted third-party code to run:

If you adopt the mobile phone software execution model, only permitted applications will be allowed to run, giving you more control to neutralize software deemed malicious, including botnets. The device can only be compromised by exploiting the monitor software (i.e., the kernel). In this way, the first thing is to have a secure seed, which most IoT devices do not comply with and is even more relevant in the case of devices that run third-party software.

Periodic System Wipe/Restore:

Restoring to a known good state will remove any junk from the system, including botnet software. When used as a preventative measure, this strategy ensures that even the most difficult to detect malware ends up in the trash.

Implement good input and output filtering practices:

Other more advanced strategies include filtering practices in network routers and firewalls. A principle of secure network design is layering: you have fewer restrictions on publicly accessible resources while at the same time tightening security for what you determine to be sensitive. Also, anything that crosses these boundaries needs to be scrutinized: network traffic, thumb drives, etc. Quality filtering increases the probability of detecting DDoS malware and its propagation and communication methods before entering or leaving the network.

If you are currently under attack, you can take steps to get rid of it. You can follow these steps to mitigate the episode if you already have Cloudflare. The DDoS protection we implement at Cloudflare is multi-dimensional to mitigate potential attack vectors. Learn more about Cloudflare's DDoS protection