Phishing is a social engineering attack where attackers trick users into revealing passwords, banking information, OTPs, or other sensitive data through fake emails, websites, SMS, or phone calls.

Remember: Phishing = Fake Message → Steal Information

Types of Phishing
Email Phishing → Fake emails pretending to be trusted organizations.
Spear Phishing → Targeted attack against a specific individual.
Whaling → Targets high-profile executives (CEO, Manager).
Smishing → Phishing through SMS.
Vishing → Phishing through voice calls.
Clone Phishing → Copies a legitimate email and replaces links/attachments.
Prevention
Verify sender identity.
Don't click suspicious links.
Enable Multi-Factor Authentication (MFA).
Use anti-phishing filters.
Check website URL (HTTPS).
Never share passwords or OTPs.

Cross-Site Scripting (XSS) is a client-side code injection attack where attackers inject malicious JavaScript into a trusted website. The script executes in the victim's browser.

Remember: XSS = Inject JavaScript into Web Page

Types of XSS
1. Stored (Persistent) XSS
Malicious script is stored permanently on the server (database, comments, forums).
Every visitor executes the script.
Remember: Stored = Saved on Server

2. Reflected (Non-Persistent) XSS
Script is not stored.
Sent through a malicious URL or form.
Executes immediately after the victim clicks the link.
Remember:Reflected = Comes Back in Response

3. DOM-Based XSS
Vulnerability exists entirely in the browser (DOM).
Server does not store or reflect the payload.
Remember:DOM = Browser-side XSS

Stored XSS                -  Reflected XSS
Payload stored on server  -  Payload comes from request
Affects all users         -  Affects only the victim clicking the link
Persistent                -  Non-persistent
More dangerous            -  Less dangerous

Prevention
Input Validation
Output Encoding
Sanitize User Input
Content Security Policy (CSP)
HttpOnly Cookies
Escape HTML characters

SQL Injection is an attack where malicious SQL commands are inserted into input fields to manipulate the database.

Remember: SQL Injection = Inject SQL Query

Effects
Bypass Login
Read Database
Modify Data
Delete Records
Gain Unauthorized Access

Prevention
Prepared Statements (Parameterized Queries)
Input Validation
Stored Procedures
Least Privilege
Escape Special Characters
Web Application Firewall (WAF)

CSRF is an attack that tricks an authenticated user into performing unwanted actions on a trusted website without their knowledge.

Remember: CSRF = Force Logged-in User to Perform Actions

Example:

A logged-in user clicks a malicious link that transfers money from their bank account.

Prevention
CSRF Tokens
SameSite Cookies
Re-authentication
CAPTCHA
Check Referer/Origin Header

Distributed Denial of Service (DDoS) is an attack where multiple compromised devices (botnet) flood a server with excessive traffic, making it unavailable to legitimate users.

Remember: DDoS = Many Attackers → One Target

Effects
Website becomes unavailable
Slow network
Service disruption
Financial loss

Prevention
Firewall
IDS/IPS
Load Balancer
Rate Limiting
CDN
DDoS Protection Services

The CIA Triad is the foundation of Information Security, ensuring that information is secure, accurate, and available to authorized users.

1. Confidentiality (C): Protects data from unauthorized access or disclosure.

Goal: Only authorized users can access sensitive information.

Methods:

Encryption
Passwords
Access Control
Multi-Factor Authentication (MFA)

Example: Online banking passwords are encrypted.

Remember: 🔒 Confidentiality = Keep data Secret

2. Integrity (I): Ensures data remains accurate, complete, and unaltered unless modified by authorized users.

Goal: Prevent unauthorized modification.

Methods:

Hashing
Digital Signatures
Checksums
Access Permissions

Example: A bank transaction amount should not be changed.

Remember: ✅ Integrity = Keep data Correct

3. Availability (A): Ensures systems and data are available whenever authorized users need them.

Goal: Minimize downtime and ensure continuous service.

Methods:

Data Backup
Redundant Systems
Disaster Recovery
UPS/Power Backup

Example: ATM services should be available 24/7.

Remember: 🌐 Availability = Keep data Accessible

1. Threat: A Threat is any potential event or action that can exploit a vulnerability and cause harm to a system, network, or data.

Examples
Malware
Hacker
Phishing attack
Fire
Flood
Insider attack

Remember: ⚠️ Threat = Potential Danger

2. Vulnerability: A Vulnerability is a weakness or flaw in a system, software, network, or process that can be exploited by a threat.

Examples
Weak password
Unpatched software
Open network ports
Misconfigured firewall
Outdated operating system

Remember: 🔓 Vulnerability = Weakness

3. Risk: A Risk is the possibility of loss or damage when a threat exploits a vulnerability.

Examples
Data theft due to weak passwords
Financial loss from ransomware
Service disruption caused by a DDoS attack

Remember: ⚡ Risk = Threat + Vulnerability → Damage

Encryption is the process of converting plaintext (readable data) into ciphertext (unreadable data) using an encryption algorithm and a key to protect data from unauthorized access.

Purpose
Protect confidentiality.
Secure data during storage and transmission.
Remember: 🔒 Encryption = Plaintext → Ciphertext

Decryption is the process of converting ciphertext back into plaintext using the correct decryption key.
Remember: 🔓 Decryption = Ciphertext → Plaintext

Symmetric Encryption: Uses the same secret key to encrypt and decrypt data.

Example: Alice encrypts a file with a secret key, and Bob uses the same key to decrypt it.

Remember: 🔑 One Key = Symmetric

Asymmetric Encryption: Uses a Public Key for encryption and a Private Key for decryption.

Example: Anyone can encrypt a message using Bob's public key, but only Bob can decrypt it using his private key.

Remember: 🔑🔑 Two Keys = Asymmetric

Authentication is the process of verifying the identity of a user or system.

It answers: "Who are you?"

Examples
Username & Password
OTP
Fingerprint
Face Recognition
Smart Card

Remember:👤 Authentication = Verify Identity

Authorization is the process of determining what an authenticated user is allowed to access or do.

It answers: "What can you do?"

Examples
Read-only access
Admin privileges
File permissions
Database access rights

Remember: 🔑 Authorization = Grant Permissions

Ransomware is a type of malware that encrypts a victim's files or locks the system and demands a ransom payment to restore access.

How It Works
Infects the computer.
Encrypts files.
Displays a ransom note.
Demands payment (often cryptocurrency).
Examples
WannaCry
LockBit
CryptoLocker
Petya
Prevention
Regular backups
Update software
Use antivirus
Avoid suspicious links and email attachments
Enable Multi-Factor Authentication (MFA)
Remember: 🔒 Ransomware = Encrypt Files → Demand Money

A Zero-Day Attack is an attack that exploits a software vulnerability before the vendor discovers or releases a security patch.

Why "Zero-Day"?: Because developers have zero days to fix the vulnerability before attackers exploit it.

Characteristics
Unknown vulnerability
No security patch available
Difficult to detect
Highly dangerous

Prevention
Regular software updates
Intrusion Detection Systems (IDS)
Endpoint protection
Network monitoring
Least privilege principle

Remember: ⚠️ Zero-Day = Unknown Vulnerability + No Patch

Social Engineering is a technique where attackers manipulate people into revealing confidential information or performing actions that compromise security.

Common Types
Phishing
Spear Phishing
Vishing (Voice)
Smishing (SMS)
Baiting
Pretexting
Tailgating

Prevention
User awareness training
Verify identity before sharing information
Never share passwords or OTPs
Enable MFA
Be cautious of unexpected emails, calls, or links

Remember: 🧠 Social Engineering = Hack the Human, Not the Computer

Cryptography is the science of securing information by converting readable data (plaintext) into unreadable data (ciphertext) using encryption algorithms.

Purpose
Confidentiality
Integrity
Authentication
Non-repudiation

Uses
Online Banking
HTTPS
VPN
Digital Signatures

Remember: 🔐 Cryptography = Protect Data using Encryption

A Cryptocurrency is a digital or virtual currency that uses cryptography for security and operates on a blockchain without a central authority (decentralized).

Characteristics
Digital currency
Decentralized
Secure transactions
Blockchain-based
Examples
Bitcoin (BTC)
Ethereum (ETH)
Litecoin

Remember: 💰 Cryptocurrency = Digital Money secured by Cryptography

Blockchain is a distributed, decentralized digital ledger that records transactions in blocks linked together using cryptographic hashes.

Characteristics
Decentralized
Immutable (difficult to change)
Transparent
Secure

Uses
Cryptocurrency
Supply Chain
Smart Contracts
Digital Identity

Remember: ⛓️ Blockchain = Chain of Blocks storing transactions

2FA is a security method that requires two different authentication factors to verify a user's identity.

Example
Password + OTP
Password + Fingerprint
ATM Card + PIN
Benefits
Better security than password alone.
Reduces unauthorized access.

Remember: 🔐 2FA = Two verification factors

MFA is a security method that requires two or more authentication factors to verify a user's identity.

Authentication Factors
Something you know → Password, PIN
Something you have → Phone, Smart Card, Security Token
Something you are → Fingerprint, Face ID, Iris Scan
Example: Password + OTP + Fingerprint

Benefits
Stronger security than 2FA.
Protects against phishing and password theft.

Remember: 🛡️ MFA = Two or More verification factors

Cyber Security is the practice of protecting computers, networks, systems, and data from cyber attacks, unauthorized access, damage, or theft.

Importance of Cyber Security
Protects sensitive data.
Prevents cyber attacks.
Ensures Confidentiality, Integrity, and Availability (CIA Triad).
Prevents financial loss.
Protects user privacy.
Maintains business continuity.
Ensures legal and regulatory compliance.
Protects critical infrastructure (banks, hospitals, government).

Remember: Cyber Security = Protect Systems + Data + Privacy

1. Phishing Fake emails/websites to steal credentials.
2. Spear Phishing Targeted phishing against a specific person.
3. Whaling Phishing targeting executives/CEOs.
4. Malware Malicious software that damages systems.
5. Virus Infects files and spreads to other files.
6. Worm Self-replicates across networks without user action.
7. Trojan Horse Malicious software disguised as legitimate software.
8. Ransomware Encrypts files and demands ransom.
9. Spyware Secretly collects user information.
10. Adware Displays unwanted advertisements.
11. SQL Injection (SQLi) Injects SQL commands to attack databases.
12. Cross-Site Scripting (XSS) Injects malicious JavaScript into web pages.
13. Cross-Site Request Forgery (CSRF) Tricks authenticated users into unwanted actions.
14. DDoS Attack Floods a server with massive traffic to make it unavailable.
15. Man-in-the-Middle (MITM) Intercepts communication between two parties.
16. Password Attack Attempts to steal or crack passwords.
17. Brute Force Attack Tries many password combinations until one works.
18. Zero-Day Attack Exploits an unknown vulnerability before a patch exists.
19. Social Engineering Manipulates people into revealing confidential information.
20. Insider Threat Attack or misuse by an authorized user within the organization

Explain Cyber Security Measures
1. Strong Password Policy
2. Multi-Factor Authentication (MFA)
3. Antivirus & Anti-malware
4. Firewall
5. Regular Software Updates
6. Data Encryption
7. Regular Backup
8. Access Control
9. User Awareness Training
10. Intrusion Detection/Prevention System (IDS/IPS)
11. Secure Network
12. Disaster Recovery Plan

A firewall is a network security system that monitors and controls incoming and outgoing traffic based on predefined security rules.

Difference Between Stateful Inspection Firewall and NGFW (Next Generation Firewall)

Given Rules:

• Rule 1: Source A → Destination B, port = 89
• Rule 2: Source A → Destination B, port < 443
• Rule 3: Source A → Destination B, port = 443

First-Match Rule Inspection:

• Firewall checks rules from top to bottom.
• As soon as a packet matches a rule, action is taken and no further rules are checked.

Case: Packet arrives with port = 443

• Check Rule 1: port 89 → ❌ Not matched
• Check Rule 2: port < 443 → ❌ 443 is NOT less than 443
• Check Rule 3: port = 443 → ✅ Matched

Final Decision:

• The packet will follow Rule 3.
• If Rule 3 action = ALLOW → packet accepted ✅
• If Rule 3 action = DENY → packet rejected ❌

Functional Requirement
The banking application shall allow users to log in using fingerprint authentication after successful fingerprint enrollment.

Security Requirement
The banking application shall securely store and verify fingerprint data using encryption and allow access only to authenticated users.

Testing a 4-Digit PIN Input Field
To test a 4-digit PIN input field in a banking application, I would verify that the system accepts only numeric values with exactly 4 digits and rejects any other input. This involves both functional testing and validation testing at the input level.

Test Cases

• Valid Input: Enter 1234 → Should be accepted (correct 4-digit number).
• Less than 4 digits: Enter 123 → Should be rejected (too short).
• More than 4 digits: Enter 12345 → Should be rejected (too long).
• Non-numeric input: Enter 12ab → Should be rejected (contains letters).
• Special characters: Enter 12@# → Should be rejected.
• Empty input: Leave the field blank → Should be rejected.

Importance of This Testing
This testing is important for security because it prevents invalid or malicious inputs that could be used to bypass authentication. It also improves reliability by ensuring that the system behaves correctly and consistently, reducing login errors and protecting user accounts.