What is Botnet? How to Prevent Botnet attacks?

Think of the damage that a hacker can do. Right from, breaking into people’s accounts, spreading fake websites, sending out dangerous spam to tricking people into handing out personal information, infecting millions with malware, and even denying access to the internet. Now imagine what a hacker can do with an army of computers at their disposal, strengthening his resources on an order of thousands and millions. This army of computers actually exists, and these are called “Botnets”.   

What is Botnet? 

Basically, a botnet is a network of infected computers which, under the command of a single master computer, work together to accomplish a goal. It may seem simple, but it is the powerhouse behind some of the worst attacks’ hackers can attempt.

A botnet includes groups of computers that have been infected with malware. A hacker remotely controls all of the computers in the group to do things like sending spam messages, generating fake web traffic, conducting DDoS attacks, serving ads to everyone in the botnet, or even forcing payment from users to be removed from the botnet.  A botnet relies on two things:

• First, it needs a large network of infected devices, called “zombies”, to do the grunt work for whatever scheme the hacker has planned.
• Second, it needs someone to actually command them to do something, which is called the Command and Control centre, or “bot herder”.

Once these things are in place, a botnet is ready to bring chaos and do harm to people and systems.

How do Botnets work?

There are two primary ways that botnets are set up, the Client-Server model and the Peer-to-Peer model.

• Client-Server Model: This is an old-fashioned way, where “zombies” receive their instructions from a single location, usually a shared server or website. So, if you want to shut down a botnet, just take down the website or server and the whole system would crumble.

• Peer-to-Peer Model: In this system, each infected machine communicates directly to a few others on the network. Those few others are connected to a few more until the whole system is strung together. So, removing one or two devices is not a problem in this model, as others can pick up the slack.

In both cases, the Command and Control owner can command and control the network. This is the reason why they use digital signatures to ensure that only commands issued by the hacker or whoever he sold the botnet to are spread through the entire network.

Types of Botnet attacks

A botnet is a network of computers or devices that have been infected with malware and can be controlled remotely by a hacker, known as a bot herder or botmaster. Botnets are commonly used for various malicious activities, including Distributed Denial-of-Service [DDoS] attacks, spamming, click fraud, data theft, and cryptocurrency mining.Let us look at the different types of botnet attacks that are commonly used by cybercriminals.

• Distributed Denial-of-Service [DDoS] Attacks: Denial-of-Service [DDoS] attacks are one of the most common types of botnet attacks. In a DDoS attack, the botnet floods a targeted website or network with traffic until it becomes overwhelmed and unable to function properly. This can result in slow response times or complete shutdown of the targeted website or network. DDoS attacks can be used for extortion, to cause damage to competitors or to advance political or ideological goals.
• Spamming and Phishing Attacks: Spamming and phishing attacks involve sending massive amounts of unsolicited emails, SMS or messages to trick recipients into clicking on a link or providing sensitive information such as login credentials or credit card numbers. Botnets are used to send spam or phishing emails, often with attachments or links that contain malware, in order to infect the recipient’s device and add it to the botnet. Spamming and phishing attacks can also be used for financial gain, such as in Business Email Compromise [BEC] scams.
• Click Fraud Attacks: Click fraud is a type of fraud where a bot clicks on an online ad in order to generate fraudulent revenue for the botmaster. In this type of attack, the botnet generates a large number of clicks on the ads, which causes the advertiser to pay for those clicks. Click fraud can be very profitable for botmasters, particularly when the targeted ad is for a high-value product or service.
• Data Theft and Espionage: Botnets can also be used for data theft and espionage. In this type of attack, the botnet is used to steal sensitive data such as financial information, trade secrets, and personal information. The botnet can be used to monitor user activity on a network, capture keystrokes, and download sensitive files. This data can then be sold on the dark web, used for identity theft or used to gain competitive advantage.
• Cryptocurrency Mining Attacks: Cryptocurrency mining is the process of validating transactions on a blockchain network and receiving rewards in the form of cryptocurrency. However, this process requires a significant amount of computing power, and some cybercriminals have turned to botnets to help them mine cryptocurrency. In this type of attack, the botnet is used to mine cryptocurrency on behalf of the botmaster, who can then sell the mined coins for a profit.
• Ransomware Attacks: Ransomware attacks involve infecting a computer or network with malware that encrypts the user’s files and demands a ransom in exchange for the decryption key. Botnets can be used to distribute ransomware to a large number of devices, making the attack more widespread and harder to contain. Ransomware attacks can be highly profitable for cybercriminals, as victims are often willing to pay the ransom to regain access to their data.
• Banking Trojans: Banking Trojans are a type of malware that is specifically designed to steal banking credentials and other financial information from the victim’s device. In a botnet-powered attack, the botnet is used to distribute the banking Trojan to a large number of devices, increasing the chances of success. Once the malware is installed, it can monitor user activity and capture login credentials and other sensitive information.

Examples of Botnet attacks:

Botnets are a network of compromised computers or devices that are under the control of a hacker, also known as a botmaster. These botnets are commonly used for various malicious activities such as DDoS attacks, spamming, click fraud, data theft, and cryptocurrency mining. Let us look at some of the real-world examples of botnet attacks that have caused significant damage and disruption.

• Mirai Botnet: One of the most notorious botnets is the Mirai botnet, which was responsible for a series of DDoS attacks in 2016 that targeted DNS provider Dyn. The attack caused major disruptions to internet services, including social media platforms, e-commerce sites, and news sites. The Mirai botnet was able to infect and control a large number of devices, including routers, security cameras, and DVRs, by exploiting weak default passwords. The botnet was eventually taken down by a collaboration between security researchers and law enforcement agencies.
• Emotet Botnet: Emotet is a botnet that was first discovered in 2014 and has since become one of the most prevalent botnets. The Emotet botnet is primarily used for distributing other malware, such as banking Trojans and ransomware. The botnet is known for its sophisticated distribution techniques, including spear-phishing emails and social engineering tactics. In 2020, Emotet was disrupted by law enforcement agencies and security researchers, resulting in a significant decrease in its activity.
• Necurs Botnet: The Necurs botnet is one of the largest botnets, with an estimated 5 million compromised devices. The botnet was primarily used for distributing spam emails and malware, including ransomware and banking Trojans. In 2020, a joint operation between law enforcement agencies and cybersecurity companies was able to take down the Necurs botnet, resulting in a significant reduction in spam emails.
• Zeus Botnet: The Zeus botnet, also known as Zbot, was a banking Trojan that infected millions of computers worldwide. The botnet was able to steal banking credentials and other financial information from the infected computers, allowing the botmaster to conduct fraudulent transactions. The Zeus botnet was responsible for the theft of millions of dollars from individuals and Organisations. 
• Avalanche Botnet: Avalanche was a botnet that was used for various criminal activities, including distributing malware and phishing emails, and conducting DDoS attacks. The botnet was able to infect over 500,000 devices worldwide and was responsible for the distribution of multiple malware families, including the TeslaCrypt ransomware. In 2016, a collaborative effort between law enforcement agencies and cybersecurity companies was able to take down the botnet.
• Waledac Botnet: The Waledac botnet was a spamming botnet that was responsible for the distribution of millions of spam emails per day. The botnet was able to infect a large number of devices, including computers, servers, and routers, and used a fast-flux technique to evade detection. The Waledac botnet was eventually taken down by Microsoft in 2010, using a combination of technical and legal measures.
• Sality Botnet: The Sality botnet was a malware family that infected computers and devices, allowing the botmaster to control them remotely. The botnet was primarily used for distributing spam emails and other malware, including the ZeuS banking Trojan. The Sality botnet was known for its resilience, as it was able to evade detection and removal by security software. 

5 ways to stop Botnets from stealing Data 

Botnet attacks are generally combined with other cyber threats, which makes its detection challenging. However, eliminating botnet threats can help businesses to stay protected from such attacks.

1. Windows firewall: This is the basic defensive tool against network-based security threats. However, users sometimes prefer to disable them to establish easy network connections. Organisations must have alternative firewall protection and also, ensure the appropriate configuration of firewalls.
2. VPN with a kill switch: A Virtual Private Network [VPN] allows access to private data through a public network. If the VPN provider has a kill switch to stop access to confidential information, the switch will hinder the transfer of data from VPN to any unsecured connection.
3. Network compartmentalization: Enterprises must have secure external and internal network communications. Compartmentalising a network facilitates in putting up access controls to limit internal communication and also monitor tracks of unexpected connections, thus highlighting the presence of a cyberattack. By limiting broad access to internal machines, the botnets can be stopped from spreading.
4. Plan a secure baseline strategy against BEC attacks: Business Email Compromise [BEC] is a common form of cyberattack that targets businesses relying on wired transactions with international suppliers. Such attacks are not easy to defend. Therefore, to end such attacks, Organisations need defensive gateway web tools.
5. A dedicated system to block fraudulent emails: Many busy users click on emails without paying much attention to them. In an Organisation, having a policy against opening random emails is not enough. While raising awareness can be of some help, the employees should be able to report suspicious emails. Additionally, employees should be prompted to update their login credentials with strong passwords, so as to create awareness of different kinds of cyberattacks and their respective real-time solutions.

Botnets are difficult to stop once they have taken control of the user’s devices. So, to reduce phishing attacks and other issues, make sure each of your devices is guarded well against this malicious hijack.

Neumetric, a cybersecurity services, consulting & products Organization, can help you reduce your security cost without compromising your security posture. Our years of in-depth experience in handling security for Organizations of all sizes & in multiple industries make it easier for us to quickly execute cost-cutting activities that do not bring value to you, while you continue focusing on the Business objectives of the Organization.

FAQs – 

Is botnet a malware?

Yes. A botnet is a type of malware that allows malicious users to control a network of computers. It can be used for many different purposes, including stealing sensitive data or performing DDoS attacks on websites.

Which malware causes botnet attacks?

Malwares such as Mirai, Emotet , Necurs , Zeus , Avalanche , Waledac, etc cause Botnet attacks.

How do I know if I am on a botnet?

Here are some signs that you may be part of a botnet:

• Slow computer performance: If your computer is running slower than usual, it could be due to a botnet running in the background.
• High CPU usage: If your CPU usage is higher than normal, it could be a sign that a botnet is using your computer’s processing power.
• Unusual network activity: If your internet connection is being used more heavily than usual, or you notice unusual network activity, it could be due to a botnet.
• Strange pop-ups: If you’re seeing strange pop-ups or advertisements, it could be a sign that your computer has been compromised.
• Antivirus alerts: If your antivirus software is alerting you to suspicious activity or malware on your computer, it could be due to a botnet infection.

How are botnets removed?

Removing a botnet from your computer can be a complex process, as it involves identifying the malware that has infected your system, and then taking steps to remove it. Here are some common steps that are taken to remove botnets:

• Disconnect from the internet: The first step is to disconnect your computer from the internet to prevent the botnet from communicating with its command and control centre.
• Run antivirus software: Run a full virus scan with your antivirus software, and make sure that it is up to date. This can help identify and remove any malware that is present on your system.
• Use specialised removal tools: Some botnets may require specialised removal tools to be removed completely. These tools are designed to target specific botnets, and may be available from the manufacturer of your antivirus software.
• Remove malicious files and processes: Once the botnet has been identified, you will need to remove any malicious files and processes associated with it. This may involve manually deleting files, or using software to remove them.
• Update security measures: After the botnet has been removed, it’s important to update your security measures, such as your antivirus software and firewall, to prevent future infections.