Understanding and Preventing SQL Injections


SQL Injection (SQLi) is one of the most notorious and commonly exploited web application vulnerabilities. It allows attackers to insert or "inject" malicious SQL code into a query, which can then be executed by the database. This can lead to unauthorized viewing of data, corrupting or deleting data, and in some cases, can grant administrative privileges on the database server.

What is SQL Injection?

When a web application takes input from a user and directly includes it within an SQL query without proper validation or escaping, it can be vulnerable to SQL injection. This essentially means that an attacker can insert malicious SQL statements into the query, which the database will then execute.

How SQL Injections Work

Imagine a login page with fields for a username and a password. Behind the scenes, when you input your credentials, the system might form a SQL query like:


If the system is not properly validating or escaping inputs, an attacker can input something like:

username: admin'--

password: [leave blank]

The SQL query then becomes:

SELECT * FROM users WHERE username='admin'--' AND password='';

The `--` is an SQL comment, which effectively nullifies the password check. This would let the attacker log in as the admin without knowing the actual password.

Common Types of SQL Injection Attacks:

Preventing SQL Injections:


SQL Injection is a serious threat to web applications but can be prevented with careful coding practices and vigilance. By understanding how these attacks work and taking the necessary precautions, developers can create more secure applications and protect sensitive data. 

Always remember: Trust no input!