=>Cyber security refers to the practice of protecting systems, networks, and data from digital attacks. These attacks often aim to access, alter, or destroy sensitive information, extort money from users, or disrupt normal business processes.
*HISTORY OF CYBER ATTACKS
The history of cyber attacks traces the evolution of digital threats from basic hacking attempts to sophisticated, large-scale attacks targeting global systems. Below is a timeline of key milestones:
1960s-1970s: Early Cyber Intrusions
1960s: The first concepts of hacking emerged as computer systems were developed. Researchers explored system weaknesses.
1971: The first known virus, "Creeper," was created by Bob Thomas. It was more of an experiment, showing how a program could move between computers.
1973: The first hacking incident occurred when an engineer from ARPANET (the predecessor to the Internet) exploited a bug in the system.
1980s: Rise of Personal Computers and Malware
1983: The movie WarGames raised public awareness of hacking. Soon after, Kevin Poulsen hacked into the U.S. Department of Defense.
1988:The Morris Worm, one of the first major worms, infected about 10% of the Internet, causing significant disruption.
1989:The first ransomware, "AIDS Trojan," was distributed via floppy disks and encrypted files, demanding a payment for decryption.
1990s: Commercial Internet and Organized Hacking
2000s: Escalation to Global Cyber Threats
2010s: Cybercrime Becomes an Industry
2020s: Modern Cyber Warfare and Sophisticated Attacks
As technology advances, cyberattacks continue to grow in scale and complexity, focusing on critical infrastructure, financial systems, and national security, with threats from criminal organizations, hacktivists, and nation-states.
* INTRUSION DETECTION SYSTEMS(IDS)
An Intrusion Detection System (IDS) is a network security tool designed to monitor, detect, and report unauthorized or malicious activity on a network or system. IDS functions by analyzing traffic patterns, monitoring system activity, and comparing this data to known attack signatures or abnormal behavior to identify potential security breaches.
*CAREERS IN CYBERSECURITY
Cybersecurity offers a wide range of career opportunities due to the increasing demand for professionals who can protect organizations from evolving digital threats. Below are some key careers in cybersecurity, along with their roles and responsibilities:
1. Cybersecurity Analyst
Role: Monitors networks and systems for suspicious activities, investigates security breaches, and implements preventive measures.
Certifications: CompTIA Security+, Certified Information Systems Security Professional (CISSP), Certified Ethical Hacker (CEH).
2. Security Engineer
Role: Designs and implements security systems and infrastructures to protect data and systems. Works on firewalls, encryption, and other security protocols.
Certifications: CISSP, Certified Information Security Manager (CISM), Certified Information Systems Auditor (CISA).
3. Ethical Hacker / Penetration Tester
Role: Performs authorized hacking to identify vulnerabilities in a system before attackers can exploit them. Conducts penetration testing and security assessments.
Skills Needed: Knowledge of hacking techniques, penetration testing tools (Metasploit, Kali Linux), and network vulnerabilities.
Role: An executive-level position responsible for an organization's overall information security strategy. Manages security teams, implements policies, and ensures regulatory compliance.
Skills Needed: Leadership, strategic planning, risk management, and knowledge of cybersecurity laws and regulations.
Certifications: CISM, CISSP, Certified in Risk and Information Systems Control (CRISC).
Hackers are individuals with expertise in computer systems, programming, and networking who use their skills to break into systems for various purposes. Hackers can be classified based on their intentions, actions, and goals. The primary types of hackers are as follows:
1. White Hat Hackers (Ethical Hackers)
Role: White hat hackers are security professionals who use their hacking skills for ethical purposes. They are often employed by organizations to identify vulnerabilities in systems and networks before malicious hackers can exploit them.
Intentions: To improve security and protect organizations from cyber threats.
Activities: Performing penetration testing, vulnerability assessments, and ethical hacking.
Example: A cybersecurity expert hired to conduct penetration testing to ensure a company's systems are secure
2. Black Hat Hackers
Role: Black hat hackers are malicious individuals who break into systems with the intention of stealing data, damaging systems, or engaging in illegal activities.
Intentions: Financial gain, data theft, espionage, or causing harm.
Example: A hacker who steals credit card information or installs ransomware to extort money from victims.
3. Gray Hat Hackers (info nothing here)
4. Script Kiddies (info nothing here)
5. Hacktivists (info nothing here)
6. State-Sponsored Hackers (Nation-State Hackers)
Role: These hackers work for governments and are tasked with hacking other countries' systems for intelligence gathering, espionage, or national security purposes.
7. Cybercriminals (info nothing here)
8. Insider Threats (Malicious Insiders)
9. Red Hat Hackers (info nothing here)
10. Blue Hat Hackers (info nothing here)
11. Green Hat Hackers (info nothing here)
12. Whistleblower Hackers (info nothing here)
BASH PROGRAMING LANGUAGE
Bash (Bourne Again Shell) is a command-line interpreter and scripting language that is widely used in Unix-based systems such as Linux and macOS. It allows users to interact with the operating system by executing commands and creating scripts to automate tasks. Here’s a brief overview of Bash programming:
Features of Bash
Command Execution: Execute system commands directly in a terminal or script.
Variables: Bash supports both user-defined and environmental variables.
MY_VAR="Hello, World!"
echo $MY_VAR
Conditional Statements: Bash includes if, else, and elif statements
if [ "$MY_VAR" = "Hello, World!" ]; then
echo "Greeting received."
else
echo "No greeting."
fi
Loops: It provides loops like for, while, and until to iterate over commands or variables.
for i in {1..5}; do
echo "Iteration $i"
done
Functions: Functions in Bash help encapsulate code for reuse
my_function() {
echo "This is a function"
}
my_function
I/O Redirection: Bash allows redirection of input and output with operators like >, <, >>, and |.
echo "Saving to file" > output.txt
cat output.txt | grep "file"
WHAT IS PHP?
PHP (Hypertext Preprocessor) is a popular open-source scripting language especially suited for web development. It is widely used to create dynamic web pages, server-side applications, and database-driven websites. PHP can be embedded directly into HTML code, making it easier to manage dynamic content on websites.
Server-Side Scripting: PHP runs on the server and outputs HTML to the browser. It is commonly used to handle backend tasks such as form handling, user authentication, and database interactions.
<?php
echo "Hello, World!";
?>
Database Interaction: PHP works well with various databases like MySQL, PostgreSQL, SQLite, etc., to create data-driven web applications.
<?php
$conn = new mysqli("localhost", "username", "password", "database");
$result = $conn->query("SELECT * FROM users");
while ($row = $result->fetch_assoc()) {
echo $row['name'];
}
?>
What is Script Kiddie?
A Script Kiddie (often shortened to skid) is a derogatory term used in the cybersecurity and hacker communities to describe an individual who uses pre-written scripts, tools, and software developed by others to perform hacking activities without fully understanding how these tools work. Script kiddies typically lack advanced knowledge of programming or networking and rely on existing exploits created by more skilled hackers.
An Access Token is a small piece of data used to verify a user’s identity after login.
It allows the user to access protected resources without logging in again.
Access tokens are commonly used in:
APIs
Web applications
Mobile apps
OAuth authentication systems
🚨 How Broken Access Token Happens
1️⃣ Token is not properly validated
2️⃣ Token is predictable
3️⃣ Token does not expire
4️⃣ Token is stored insecurely (like in localStorage)
5️⃣ Token is sent over HTTP instead of HTTPS
🔓 What is Broken Access Control?
Broken Access Control is a security vulnerability where a web application does not properly restrict what authenticated users are allowed to do.
👉 This means a normal user may be able to:
View other users’ data
Modify records
Access admin pages
Delete or update sensitive information
Simple Definition
Broken Access Control occurs when an application fails to properly enforce user permissions, allowing unauthorized actions.
🔐 What is Cryptographic Failure?
Cryptographic Failure is a security vulnerability that occurs when sensitive data is not properly protected using encryption.
Cryptographic Failure occurs when an application fails to properly encrypt or protect sensitive data such as passwords, credit card numbers, or personal information.
🔎 What is Cryptography?
Cryptography is the technique of:
Encrypting data 🔒
Decrypting data 🔓
Protecting information from unauthorized access
1️⃣ Cryptographic Failure
Cryptographic Failure happens when sensitive data is not properly encrypted, hashed, or protected.
Cryptographic Failure occurs when an application fails to properly protect sensitive information using strong encryption.
🔎 Examples:
Storing passwords in plain text
Not using HTTPS
Using weak hashing (like MD5)
Exposed encryption keys
💥 Risk:
Data theft
Password leaks
Identity theft
🛡️ Prevention:
Use HTTPS
Hash passwords (bcrypt, Argon2)
Use strong encryption (AES-256)
Secure key management
💉 2️⃣ SQL Injection (SQLi)
SQL Injection is a type of Injection attack where an attacker inserts malicious SQL code into a query to manipulate the database.
Simple Definition:
SQL Injection is a vulnerability that allows attackers to execute malicious SQL queries to access or modify database data.
Insecure Design
Insecure Design is a security vulnerability that happens when an application is designed without proper security controls from the beginning.
Insecure Design means security was not properly considered during the design phase of the application.
Example
No limit on login attempts → allows brute force attack
No proper validation flow in payment system
Missing access control planning
Security Misconfiguration
Security Misconfiguration occurs when security settings are improperly configured or left as default.
Security Misconfiguration happens when security settings are not properly configured, leaving the system vulnerable.
⚠️ Vulnerable and Outdated Components
Vulnerable and Outdated Components means an application is using software, libraries, frameworks, or plugins that have known security weaknesses and are not updated.
Vulnerable and Outdated Components occur when an application uses old or insecure software components that contain known security vulnerabilities.
🔐 Identification and Authentication Failures
Identification and Authentication Failures happen when an application does not properly verify a user’s identity.
Simple Definition
Identification and Authentication Failures occur when an application improperly handles login, user identity verification, or session management, allowing attackers to gain unauthorized access
Software and Data Integrity Failures
Software and Data Integrity Failures occur when an application does not properly verify that its software updates, code, or data have not been tampered with.
Software and Data Integrity Failure happens when software updates, code, or data are not properly verified, allowing attackers to modify or inject malicious content.
Security Logging and Monitoring Failures
Security Logging and Monitoring Failures happen when an application does not properly record (log) security events or fails to monitor them.
Security Logging and Monitoring Failure occurs when a system does not properly log, detect, or respond to security-related events and attacks.
🌐 Server-Side Request Forgery (SSRF)
Server-Side Request Forgery (SSRF) is a vulnerability where an attacker tricks the server into making requests to unintended locations.
SSRF is a vulnerability that allows an attacker to force a server to make unauthorized requests to internal or external systems.
Social Engineering is a type of cyber attack where attackers manipulate people into giving confidential information, rather than hacking systems directly.
Social engineering is the psychological manipulation of people to gain access to sensitive information like passwords, OTPs, bank details, or personal data.
🌐 What is TCP?
🔹 TCP = Transmission Control Protocol
TCP is a connection-oriented protocol used to send data reliably over a network.
It works at:
Transport Layer (Layer 4) of the OSI model
✅ Features of TCP:
Reliable (guarantees delivery)
Ordered data transfer
Error checking
Retransmission of lost packets
3-way handshake before sending data
📦 Example Uses:
Web browsing (HTTP/HTTPS)
Email
File transfer (FTP)
Online banking
⚡ What is UDP?
🔹 UDP = User Datagram Protocol
UDP is a connectionless protocol used for fast communication.
It also works at:
Transport Layer (Layer 4)
✅ Features of UDP:
Faster than TCP
No connection setup
No guaranteed delivery
No retransmission
No ordering
📦 Example Uses:
Online games 🎮
Video streaming 📺
Live calls (Zoom, WhatsApp calls)
DNS queries
🌐 What is IoT Security?
🔹 IoT = Internet of Things
IoT Security means protecting Internet-connected smart devices from cyber attacks.
IoT devices include:
Smart TVs
Smart bulbs
CCTV cameras
Smartwatches
Smart home locks
Industrial sensors
These devices connect to the internet and communicate using protocols like TCP/UDP.
IoT Security is the practice of protecting connected devices and networks in the Internet of Things ecosystem.
🔐 1️⃣ Social Engineering
Social Engineering = Psychological manipulation of people to get confidential information.
Instead of hacking systems, attackers hack humans.
Targets:
Passwords
OTP
Bank details
Personal information
📧 2️⃣ Phishing
Phishing = Fake emails or websites pretending to be real companies.
Example:
Fake email from:
Google
State Bank of India
Message:
“Your account will be blocked. Click here to verify.”
When you click → Fake website steals your login details.
📱 3️⃣ Smishing
Smishing = SMS + Phishing
Attack happens through text message.
Example:
“You won ₹10,000. Click this link.”
Fake SMS link → Malware or data theft.
📞 4️⃣ Vishing
Vishing = Voice Phishing
Scammer calls pretending to be:
Bank officer
Police officer
Customer care
They ask:
“Tell me your OTP to verify your account.”
If you share → Money stolen 💸
🐋 5️⃣ Whaling
Whaling = Phishing attack targeting big people like:
CEO
Managers
Company directors
It targets “big fish” 🐋 (high-level executives).
Example:
Fake legal email sent to company CEO.
🚪 6️⃣ Tailgating
Tailgating = Physically following someone into a secure building without permission.
Example:
An attacker:
“I forgot my ID card. Please open the door.”
Employee opens → Attacker enters secure area.
👀 7️⃣ Shoulder Surfing
Shoulder Surfing = Watching someone type password or PIN.
Example:
ATM PIN spying
Looking at laptop screen in public
Watching login details in café
1️⃣ Social Engineering
Social Engineering is the psychological manipulation of people to obtain confidential or sensitive information.
2️⃣ Phishing
Phishing is a cyber attack in which attackers send fake emails or create fake websites pretending to be trusted organizations to steal user information.
3️⃣ Smishing
Smishing is a type of phishing attack carried out through SMS (text messages) to trick victims into sharing sensitive data.
4️⃣ Vishing
Vishing (Voice Phishing) is a social engineering attack conducted through phone calls to obtain confidential information.
5️⃣ Whaling
Whaling is a phishing attack that specifically targets high-level executives such as CEOs or managers.
6️⃣ Tailgating
Tailgating is a physical security breach where an unauthorized person follows an authorized person into a restricted area.
7️⃣ Shoulder Surfing
Shoulder Surfing is the act of spying on someone to obtain sensitive information like passwords or PIN numbers by observing their screen or keyboard.
🔥 What is Zphisher?
Zphisher is an open-source phishing tool used to create fake login pages that look like real websites in order to capture user credentials (like username and password).
It is mainly used for:
Cybersecurity learning
Ethical hacking practice
Security awareness testing
Zphisher is a phishing tool used to generate fake web pages that imitate popular websites to collect login credentials.
🛠️ How It Works (Basic Idea)
Attacker selects a target website template (like social media or banking).
Zphisher generates a fake login page.
Victim clicks the link and enters credentials.
The tool captures and displays the entered data.
🔐 What is Cryptography?
Cryptography is the technique of protecting information by converting it into a secret code so that only authorized people can read it.
Cryptography is the process of converting plain text into unreadable form (cipher text) to secure data from unauthorized access.
Basic Terms
Plaintext → Original readable message
Ciphertext → Encrypted unreadable message
Encryption → Converting plaintext into ciphertext
Decryption → Converting ciphertext back to plaintext
Key → Secret value used for encryption & decryption
1️⃣ Symmetric Key Cryptography
Same key used for encryption & decryption
Faster
Example: AES
2️⃣ Asymmetric Key Cryptography
Two keys: Public key & Private key
More secure for communication
Example: RSA
3️⃣ Hashing
Converts data into fixed-length value
One-way process (cannot reverse)
Example: SHA
🔐 What is CyberChef?
CyberChef is a free online tool used for data analysis, encoding, decoding, encryption, hashing, and cybersecurity investigations.
It is often called:
“The Cyber Swiss Army Knife” 🛠️
CyberChef is a web-based cybersecurity tool used to analyze, decode, encode, encrypt, and manipulate data.
A Backdoor is a hidden method used to bypass normal authentication and gain unauthorized access to a system.
A backdoor is like a secret entry door into a computer or network that allows attackers to enter without a password.
Even if the main security is strong, the attacker can enter through the backdoor.
🔁 What is Persistence?
Definition
Persistence is the technique used by attackers to maintain long-term access to a compromised system, even after reboot or password change.
Persistence ensures:
“Even if the system restarts, I still have access.”
🌐 What is a VPN?
🔹 VPN = Virtual Private Network
A VPN is a technology that creates a secure, encrypted connection between your device and the internet.
A VPN is a network service that encrypts your internet connection and hides your IP address to provide privacy and security.
🔐 What Does a VPN Do?
1️⃣ Hides Your IP Address
Your real IP address is hidden and replaced with the VPN server’s IP.
So websites cannot see your real location.
2️⃣ Encrypts Your Data
VPN encrypts your internet traffic.
Even if someone intercepts your data (like on public WiFi), they cannot read it.
3️⃣ Protects on Public WiFi
When using WiFi in:
Cafes ☕
Airports ✈
Hotels 🏨
VPN prevents hackers from spying.
4️⃣ Changes Your Virtual Location
You can connect to servers in different countries.
Example:
If you connect to a US server → websites think you're in the USA.
How It Works
Without VPN:
You → Internet → Website (visible)
With VPN:
You → Encrypted Tunnel → VPN Server → Website (hidden & secure)
🌐 What is an IP Address?
🔹 IP = Internet Protocol
An IP address is a unique number assigned to every device connected to a network or the internet.
It works like a home address for your device 📍
An IP address is a unique numerical identifier used to identify and communicate with devices on a network.
🌐 How Internet Works?
The Internet is a global network of interconnected computers that communicate using IP addresses and protocols like TCP/IP.
What Happens When You Open a Website?
Let’s say you open google.com
1️⃣ You Type Website Name
Your browser sends a request.
2️⃣ DNS Converts Name to IP
Domain name → converted into IP address
Example: google.com → some IP address
3️⃣ Request Travels Through ISP
Your ISP (Internet Service Provider) sends your request through routers.
4️⃣ Server Responds
The website server sends data back to your IP address.
5️⃣ Browser Displays Website
Done
🔐 How VPN Works?
Now let’s add VPN.
A VPN creates an encrypted tunnel between your device and a VPN server to hide your IP and protect your data.
1️⃣ You Connect to VPN
Your device connects to VPN server.
2️⃣ Encrypted Tunnel Created
All your data becomes encrypted.
3️⃣ VPN Server Sends Request
Instead of your real IP, the VPN server sends request to website.
4️⃣ Website Responds to VPN
Website sends data to VPN server.
5️⃣ VPN Sends Back to You
🔄 VPN Communication Flow
You → 🔐 Encrypted Tunnel → VPN Server → Website → VPN → You
🖥️ VPN Installation on Windows (Step-by-Step)
Below are two common ways to use a VPN on Windows 10/11.
Method 1: Install a VPN App
This is the most common method.
🔹 Steps:
1️⃣ Choose a VPN provider (example: Proton VPN, NordVPN, ExpressVPN)
2️⃣ Go to the official website
3️⃣ Download the Windows app
4️⃣ Install it like normal software
5️⃣ Login
6️⃣ Click Connect
Done
Method 2: Manual VPN Setup
Windows has a built-in VPN feature.
🔹 Steps:
1️⃣ Open Settings
2️⃣ Go to Network & Internet
3️⃣ Click VPN
4️⃣ Click Add a VPN connection
Fill the details:
VPN provider → Windows (built-in)
Connection name → Any name
Server name or address → Provided by VPN provider
VPN type → Automatic / L2TP / PPTP (given by provider)
Username & Password → Provided by VPN
5️⃣ Click Save
6️⃣ Click Connect
🔐 How to Install OpenVPN on Windows
OpenVPN is an open-source VPN software used to create secure encrypted connections.
An ISP is a company that provides you access to the Internet.
An ISP (Internet Service Provider) is a company that supplies internet connection services to individuals and organizations.
🔄 How ISP Works (Simple Flow)
You → Router → ISP → Internet → Website → Back to You
Without ISP, you cannot access the internet.
🦈 What is Wireshark?
🔹 Wireshark
Wireshark is a network packet analyzer used to capture and analyze network traffic in real time.
Wireshark is a network analysis tool used to capture and examine data packets traveling across a network.
🧅 What is Onion Routing?
🔹 Onion Routing
Onion Routing is a technique used to provide anonymous communication over the internet by encrypting data in multiple layers.
Onion Routing is a method of anonymous communication where data is encrypted in multiple layers and passed through several network nodes to hide the sender’s identity.
🌑 What is Dark Web?
The Dark Web is a hidden part of the internet that cannot be accessed using normal web browsers and requires special software like Tor to access.
🌐 Internet Has 3 Parts
1️⃣ Surface Web
Normal websites
Google, YouTube, news sites
Searchable by search engines
2️⃣ Deep Web
Not indexed by search engines
Login pages (banking, email)
Private databases
3️⃣ Dark Web
Hidden networks
Requires special browser (Tor)
Uses .onion domains
🔐 How Dark Web Works
Dark Web uses:
Onion Routing
Encrypted communication
Anonymous servers
Access example:
You → Tor network → .onion website
💻 What is Tails OS?
🔹 Tails OS
Tails (The Amnesic Incognito Live System) is a privacy-focused Linux operating system designed to protect your anonymity and security.
Tails OS is a secure and anonymous operating system that runs from a USB drive and leaves no trace on the computer after shutdown.
How It Works
Install Tails on USB Boot computer from USB System runs independently All traffic goes through Tor Shut down → No history saved
🏁 What is CTF?
🔹 CTF = Capture The Flag
In cybersecurity, a CTF (Capture The Flag) is a competition where participants solve security challenges to find hidden “flags”
CTF is a cybersecurity competition in which players solve hacking-related challenges to capture hidden flags.
🔥 Types of CTF Challenges
1️⃣ Web Exploitation
SQL Injection
XSS
Authentication bypass
2️⃣ Cryptography
Breaking ciphers
Hash cracking
Encoding/decoding
3️⃣ Forensics
Analyzing files
Extracting hidden data
Log analysis
4️⃣ Reverse Engineering
Understanding program behavior
Finding hidden logic
5️⃣ Network / Packet Analysis
Using tools like Wireshark
Inspecting traffic
6️⃣ OSINT (Open-Source Intelligence)
Finding information from public sources
🏆 Types of CTF Competitions
🔹 Jeopardy Style
Solve different categories
Each challenge has points
🔹 Attack-Defense
Defend your server
Attack other teams
🎯 Why CTF Is Important?
✔ Improves hacking skills
✔ Practical cybersecurity learning
✔ Good for resume
✔ Prepares for CEH & security jobs
✔ Fun way to learn 🔥
🚩 What is a Flag?
A flag is a secret piece of text hidden inside a cybersecurity challenge that proves you successfully solved it.
🏁 Why It’s Called “Capture The Flag”?
The name comes from a traditional game where players capture the opponent's flag 🏃♂️
In cybersecurity:
Instead of a physical flag, you capture a digital secret.
🏁 Types of CTF Challenges
1️⃣ Web Exploitation
Web Exploitation challenges involve finding and exploiting vulnerabilities in web applications such as SQL Injection, Cross-Site Scripting (XSS), authentication bypass, and misconfigurations to capture hidden flags.
These challenges test understanding of how websites work and how security flaws can be abused.
2️⃣ Cryptography
Cryptography challenges focus on breaking encryption, decoding encoded messages, cracking hashes, or solving cipher-based puzzles to reveal hidden flags.
These tasks test knowledge of encryption algorithms, hashing techniques, and encoding methods.
3️⃣ Forensics
Forensics challenges require analyzing digital evidence such as files, logs, memory dumps, or network captures to uncover hidden information or flags.
Participants may use tools like Wireshark to inspect packet data.
4️⃣ Reverse Engineering
Reverse Engineering challenges involve analyzing compiled programs or binaries to understand their logic and discover hidden secrets or flags.
This category tests knowledge of assembly code, debugging, and program analysis.
5️⃣ OSINT (Open-Source Intelligence)
OSINT challenges require gathering publicly available information from the internet, social media, websites, and metadata to solve puzzles and find flags.
These challenges test investigation and research skills without hacking.
6️⃣ Steganography
Steganography challenges involve hiding and detecting secret information inside images, audio files, or other media formats.
Participants must extract hidden messages embedded within files.
What is TryHackMe? (Complete Beginner Guide)
Introduction
TryHackMe is an online cybersecurity training platform that helps beginners and professionals learn ethical hacking and security skills through hands-on practice.
It provides virtual labs where users can practice real-world cybersecurity techniques in a safe and legal environment.
TryHackMe is an online platform that teaches cybersecurity using interactive lessons and virtual hacking labs.
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