Comprehensive Guide to SQL Injection Attacks: Understanding and Prevention | By Gentil Security
SQL Injection (SQLi) is one of the most critical and prevalent web application vulnerabilities. By exploiting SQL Injection, attackers can manipulate an application’s database queries, often leading to unauthorized access, data breaches, or even full compromise of the backend database.
This article aims to provide a detailed explanation of SQL Injection, its different types, how it works, and effective prevention strategies to safeguard your applications.
What is SQL Injection?
SQL Injection is a code injection technique where malicious SQL statements are inserted into input fields to manipulate the backend database. It occurs when user input is improperly sanitized and executed directly within SQL queries.
Why Should You Care About SQL Injection?
- Real-World Impact: SQLi attacks have led to data breaches in well-known companies, costing millions of dollars.
- Relevance in Bug Bounty Programs: Many platforms reward researchers for finding SQL Injection vulnerabilities, making it a lucrative skill for ethical hackers.
If you’re serious about cybersecurity, SQL Injection is a must-know topic.
Types of SQL Injection
SQL Injection can be categorized into several types, including:
- Classic SQL Injection (In-band)
- Attackers directly interact with the database using standard queries and retrieve data via the application’s response.
2. Blind SQL Injection
- Exploits database queries without direct feedback. Results are inferred based on true/false conditions.
3. Error-based SQL Injection
- Exploits database error messages to extract information about the structure of the database.
4. Out-of-Band SQL Injection
- Uses external channels (like DNS or HTTP requests) to extract data from the database.
Hands-On: How SQL Injection Works
Here’s an example of a vulnerable SQL query:
SELECT * FROM users WHERE username = '" + userInput + "' AND password = '" + userPassword + "';If user input is not sanitized, an attacker can enter malicious input like:
username: ' OR 1=1 --
password: (empty)The resulting query becomes:
SELECT * FROM users WHERE username = '' OR 1=1 --' AND password = '';This query always returns true because of the OR 1=1 condition, allowing attackers to bypass authentication.
Watch the Video Tutorial: Beginner’s Guide to SQL Injection
Understanding theory is great, but practice is key. In this video, I explain:
- The basics of SQL Injection.
- How to exploit vulnerabilities safely in a controlled environment.
- Tips to sharpen your bug bounty hunting skills.
Watch the video here: شرح SQL Injection للمبتدئين بالعربي بالتفصيل | دورة Bug Bounty 2025
Steps to Prevent SQL Injection
- Use Prepared Statements (Parameterized Queries):
- Avoid dynamically constructing SQL queries. Use parameterized queries with placeholders to separate user input from the SQL code.
2. Input Validation:
- Strictly validate user inputs using whitelists. Reject unexpected characters and sanitize input fields.
3. Escape User Inputs:
- Properly escape special characters to prevent them from interfering with SQL queries.
4. Use Stored Procedures:
- Encapsulate database logic in stored procedures rather than relying on direct SQL statements in the application.
5. Limit Database Privileges:
- Assign the minimum required privileges to database accounts used by the application.
6. Regularly Update and Patch Software:
- Ensure that your database and application frameworks are updated with the latest security patches.
Additional Learning Resource
For a detailed breakdown of SQL Injection attacks, practical examples, and solutions, check out the full explanation on my Notion page:
👉 SQL Injection: SQL injection | by Gentil Security
SQL Injection is not just a vulnerability; it’s a gateway for hackers to access sensitive data. As a beginner, mastering this topic opens doors to a deeper understanding of web security and bug bounty hunting.
Don’t stop here — watch the video, practice on labs like PortSwigger’s Web Security Academy, and start applying what you’ve learned.
Are you ready to take the first step toward becoming a cybersecurity expert? Let’s go! 🚀
