Cybersecurity & VPN

What is Cybersecurity?

Cybersecurity is the practice of protecting computers, networks, programs, and data from unauthorized access, attacks, or damage.

flowchart TD
CIA((CIA Triad))
CIA --> C["🔒 Confidentiality<br/>Only authorized access"]
CIA --> I["✅ Integrity<br/>Data not altered"]
CIA --> A["🌐 Availability<br/>Systems accessible when needed"]

CIA Triad — Foundation of Security

Types of Cyber Attacks

Social Engineering Attacks

Network Attacks

Malware Types

Malware (Malicious Software) is any software designed to harm or exploit computers.

Key difference: Virus needs a host file; Worm spreads independently. Trojan doesn’t replicate — it opens a backdoor.

flowchart TD
M["🦠 Malware"]
M --> V["Virus<br/>(Needs host file)"]
M --> W["Worm<br/>(Self-replicates<br/>via network)"]
M --> T["Trojan<br/>(Disguised,<br/>opens backdoor)"]
M --> R["Ransomware<br/>(Encrypts files,<br/>demands payment)"]
M --> S["Spyware<br/>(Monitors<br/>user activity)"]
M --> K["Keylogger<br/>(Records<br/>keystrokes)"]

Zero Trust Security Model

Zero Trust = “Never trust, always verify”

• No device or user is trusted by default, even inside the network
• Every access request is authenticated and authorized
• Principle of Least Privilege — give minimum access needed
• Micro-segmentation — divide network into small zones
• Continuously monitors and validates users

Traditional security trusts everything inside the firewall. Zero Trust trusts nothing.

VPN (Virtual Private Network)

A VPN creates an encrypted tunnel between your device and a remote server, making your internet connection private and secure.

How VPN Works

sequenceDiagram
participant You as Your Device
participant VPN as VPN Server
participant Web as Internet/Website

You->>VPN: 1. Encrypted data via tunnel
VPN->>Web: 2. Decrypted request forwarded
Web-->>VPN: 3. Response received
VPN-->>You: 4. Re-encrypted response via tunnel

1. Your data is encrypted before leaving your device
2. Encrypted data travels through a secure tunnel to the VPN server
3. VPN server decrypts and forwards your request to the internet
4. Response follows the same encrypted path back

Types of VPN

VPN Tunneling Protocols

Firewalls

A Firewall monitors and controls incoming/outgoing network traffic based on security rules. It acts as a barrier between trusted and untrusted networks.

Encryption & Cryptography

Encryption converts readable data (plaintext) into unreadable form (ciphertext) using a key.

sequenceDiagram
participant A as Alice (Sender)
participant B as Bob (Receiver)

Note over A,B: Asymmetric Encryption (RSA)
A->>A: Encrypt with Bob's PUBLIC key
A->>B: Send encrypted message
B->>B: Decrypt with own PRIVATE key

Symmetric vs Asymmetric Encryption

Hashing

Converts data into a fixed-length string. One-way — cannot be reversed.

Digital Signature & Certificate

• Digital Signature — proves the sender’s identity and data integrity (uses sender’s private key)
• Digital Certificate — issued by Certificate Authority (CA), verifies website identity (SSL certificate)
• SSL/TLS — encrypts data between browser and server (used in HTTPS)

Authentication Methods

Three authentication factors: Something you know (password), something you have (phone/token), something you are (biometric).

Indian Cyber Security Framework

Famous Ransomware Attacks

WannaCry was stopped by a security researcher who found a “kill switch” domain. It highlighted the danger of unpatched systems.

Important Sections of Indian IT Act

IT Act 2000 — Key Facts

• India’s first cyber law, enacted on 17 October 2000
• Amended in 2008 — added new cybercrime sections (66A-66F, later 66A struck down by Supreme Court in 2015)
• Governs e-commerce, digital signatures, and cybercrime
• Recognizes electronic documents and digital signatures as legally valid

HTTPS, TLS & End-to-End Encryption

Advanced Security Concepts

Types of Hackers

CERT-In Mandatory Reporting (2022)

In April 2022, CERT-In issued a directive requiring:

• All organizations must report cybersecurity incidents within 6 hours of detection
• Applies to data breaches, ransomware, DDoS attacks, unauthorized access
• VPN providers must maintain user logs for 5 years
• Cloud and VPN service providers must register user details

This is one of the strictest incident reporting timelines in the world. Non-compliance can lead to penalties under IT Act.

Key Takeaways

• CIA Triad: Confidentiality, Integrity, Availability — foundation of security
• Phishing = fake emails; Spear Phishing = targeted; Whaling = executives; Vishing = voice; Smishing = SMS
• Virus needs host; Worm self-replicates; Trojan opens backdoor; Ransomware encrypts & demands payment
• WannaCry (2017): exploited Windows SMB vulnerability, 150+ countries, 200K+ computers, Bitcoin ransom
• Petya/NotPetya (2017): targeted Ukraine, spread globally, actually a wiper (destroyed data permanently)
• Zero Trust = “Never trust, always verify” — Least Privilege + Micro-segmentation
• VPN creates encrypted tunnel; WireGuard (newest, fastest) & OpenVPN (open-source, strong)
• Symmetric (same key, AES/DES) is faster; Asymmetric (2 keys, RSA/ECC) is for key exchange
• Hashing: MD5 (128-bit, insecure), SHA-256 (256-bit, blockchain), SHA-512 (512-bit)
• Digital Signature proves identity (private key); Digital Certificate issued by CA; PKI manages certificates
• TLS 1.3 = latest, faster & more secure; HTTPS uses port 443
• E2EE (End-to-End Encryption): only sender & receiver can read — WhatsApp uses Signal Protocol
• Honeypot = decoy system to attract hackers; Zero-day = flaw exploited before patch exists
• White Hat = ethical; Black Hat = criminal; Grey Hat = unauthorized but non-malicious
• IT Act 2000: enacted Oct 17, 2000; India’s first cyber law; governs e-commerce, digital signatures, cybercrime
• Section 43 = unauthorized access (up to Rs 1 crore); Section 66 = hacking (3 yrs); Section 67 = obscene content (5 yrs); Section 72 = privacy breach (2 yrs)
• CERT-In 6-hour rule (April 2022): mandatory incident reporting within 6 hours; VPN providers must keep logs 5 years
• Authentication factors: Know (password), Have (phone/token), Are (biometric)

Summary Cheat Sheet