Introduction of Botnet in Computer Networks (original) (raw)

Last Updated : 13 Jun, 2026

A botnet is a network of compromised computers or devices infected with malware and remotely controlled by an attacker (botmaster) through a Command and Control (C&C) system. These infected devices are called bots or zombies.

• Botnets are created using malware such as trojans, worms or spyware.
• Each infected device becomes part of a remotely controlled network.
• Bots operate in the background without user knowledge.

Botnet

Botnet Working and Communication

The process involves infection, connection, communication, execution of commands and expansion of the botnet.

Step 1: Identifying Vulnerable Systems

The attacker first scans and identifies devices that can be easily compromised. These systems usually have weak security or outdated protection, making them easy entry points for malware infection.

• Outdated operating systems or unpatched software.
• Weak or default passwords and Poorly configured security settings.
• Users who frequently click unknown links or download unsafe files.

Step 2: Malware Infection

The attacker spreads malicious software to the identified systems using different delivery methods. Once executed, the malware installs itself silently and turns the device into a bot without the user noticing.

• Phishing emails with malicious attachments or links.
• Fake software updates or cracked software downloads.
• Infected websites (drive-by downloads).

Step 3: Connection to Command and Control (C&C) Server

After infection, the device connects to a Command and Control server. This server acts as the control center where the attacker manages all infected devices remotely.

• Bot registers itself with the C&C server.
• Sends device information like IP address and system details.
• Waits for instructions from the botmaster and Enables remote control of infected systems.

Step 4: Communication Using Common Protocols

Botnets communicate using standard internet protocols to avoid detection. The traffic is designed to look normal so that it blends with regular network activity.

• IRC (Internet Relay Chat) used in older botnets.
• HTTP/HTTPS traffic to mimic normal web browsing.
• Peer-to-Peer (P2P) communication without central server dependency.

Step 5: Execution of Commands

The botmaster sends instructions through the C&C system and infected devices carry out tasks automatically. These actions are often large-scale and coordinated.

• Sending spam emails in bulk.
• Launching Distributed Denial-of-Service attacks.
• Redirecting users to phishing or malicious websites.

Step 6: Botnet Expansion (Self-Propagation)

The botnet continues to grow by infecting more vulnerable systems. Each newly infected device becomes part of the network, increasing its strength and reach.

• Infecting new systems using similar attack methods.
• Increasing overall size and attack capability of the botnet.

Types of Botnets

Botnets can be classified based on the communication channel used between the bots and the Command and Control (C&C) server.

1. IRC Botnet

This botnet uses Internet Relay Chat (IRC) servers as the Command and Control (C&C) channel through which the botmaster sends instructions to infected devices.

• Uses centralized communication structure.
• Bots connect to an IRC server to receive instructions.
• Commands are transmitted as normal chat messages.

2. Peer-to-Peer (P2P) Botnet

This operates using a decentralized network structure where each infected device communicates directly with other bots instead of relying on a central server.

• Does not depend on a central Command and Control server.
• Each bot acts as both client and server.
• Bots share commands with each other across the network.

3. HTTP/HTTPS Botnet

Bots periodically connect to specific URLs to receive instructions, making the traffic appear similar to normal web browsing activity.

• Uses web protocols for communication.
• Bots connect to web servers at regular intervals.
• Communication blends with normal internet traffic.

Types of Botnet Attacks

• **Phishing Attack: This attack uses botnets to send fraudulent messages that trick users into revealing sensitive information such as passwords, credit card details or login credentials.
• **DDos Attack: Multiple bots send a large amount of traffic to a target server, making the website or service slow or unavailable to legitimate users by common techniques include SYN Flood, UDP Flood.
• **Spamming: Attack in which botnets send a large number of unwanted emails or messages automatically.
• **Data Theft: This involves stealing confidential or sensitive information using botnets.
• **Targeted Intrusion: This attack focuses on a specific organization or individual to gain unauthorized access to valuable data or systems.

Botnet Prevention Methods

• Keep operating system and software updated with latest security patches.
• Avoid clicking suspicious links, emails or unknown attachments.
• Use strong and unique passwords for different accounts.
• Enable two-factor authentication (2FA) for additional security.
• Install trusted antivirus or endpoint security software.
• Use firewall to monitor and control incoming and outgoing network traffic.
• Download software only from trusted and official sources.