In-band SQL Injection (Classical SQLI)

1- 🐞 Error-Based SQL Injection

Definition

Error-Based SQLi is a technique that takes advantage of database error messages to extract useful information about the database structure or content.

🔍 How It Works

When a malicious SQL query is injected and causes an error, the application returns an error message that may reveal details like:

• Table names
• Column names
• Database version
• SQL syntax behavior

These messages help the attacker map out the structure of the backend database.

🛠️ Example

Vulnerable Query:

SELECT * FROM users WHERE id = '1';

Injected Input:

1' AND 1=CONVERT(int, (SELECT @@version))--

If the database returns an error like:

Conversion failed when converting the varchar value 'Microsoft SQL Server...' to data type int