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Cyber Security Academy · Lesson

SQL Injection: How and Why It Works

Understand classic, blind, and out-of-band SQLi and why parameterized queries prevent it.

What is SQL Injection?

SQL Injection (SQLi) occurs when user-supplied input is included in a SQL query without proper sanitization, allowing attackers to manipulate the query logic. It is one of the oldest and most damaging web vulnerabilities.

How SQL Injection Works

A login form queries: SELECT * FROM users WHERE username='INPUT' AND password='INPUT'

If the attacker enters ' OR 1=1-- as username, the query becomes: SELECT * FROM users WHERE username='' OR 1=1--' AND password='...' — which returns all users.

All lessons in this course

  1. SQL Injection: How and Why It Works
  2. Cross-Site Scripting (XSS)
  3. Cross-Site Request Forgery (CSRF)
  4. Security Misconfiguration and Exposed Services
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