What is SQL Injection ?

SQL Injection is a attack against websites / web applications which are using SQL Database.

Simply, Hacker will insert malicious SQL command and takeover the database.

How Does it Work?

Let's say, You have a code like this,

<?php

       $username = $_POST['username'];
       $password = md5($_POST['password']); 
       $sql = "SELECT * FROM `users` WHERE username = '$username' AND password = '$password'";
       
?>

If user input,
Username : admin
Password : admin123

The SQL will looks like,

SELECT * FROM `users` WHERE username = 'admin' AND password = '0192023A7BBD73250516F069DF18B500'

It will works fine,

But If user input,

If your input,
Username : admin' OR 1 = 1 --
Password : admin123

The SQL will looks like,

SELECT * FROM `users` WHERE username = 'admin' OR 1 = 1 --' AND password = '0192023A7BBD73250516F069DF18B500'

Here you can see, The password query will be commented (Will not Execute).
And 1 = 1 is always true, The hacker can get all the information of Users.

They can delete or change any record too.

Click Here | Watch SQl Injection tutorial

SQL Injection Strings

Click Here | Some injection Strings

How to prevent SQL Injections?

Nowadays, Most of the back-end frameworks handle injections itself. But If you don't use any frameworks, You can do it manually.

Every language has built-in functions for handle SQL injections while binding data.

PHP
PyTHON
.NET
NodeJS
Java