SQL INJECTION attack what it is and how to defend ourselves

SQL injection is one of the most common and dangerous vulnerabilities affecting web applications. This form of attack exploits weaknesses in the way a web application interacts with a Structured Query Language (SQL)-based database to gain unauthorized access to data or perform unwanted operations. In this article, we will detail what SQL injection attacks are, how they work, and steps that can be taken to prevent them.

What are SQL injection attacks?

SQL injection attacks occur when an attacker exploits a vulnerability in the Web application to inject malicious SQL code into queries sent to the database. This can allow the attacker to manipulate queries, obtain sensitive data, modify or delete data, or perform other malicious actions. The main reason SQL injection attacks are so prevalent is that many web applications do not properly validate user input before including it in SQL queries, thus opening the door to attacks.

How do SQL injection attacks work?

To better understand how SQL injection attacks work, it is useful to have a basic understanding of the SQL language and its use in Web applications. SQL is used to query and manipulate relational databases, allowing applications to access stored data.

When a Web application interacts with a SQL database, it usually does so by sending queries to the database to obtain the requested data. These queries contain SQL statements that are interpreted by the database to perform the desired action. For example, a web application might send a query to the database to obtain the list of registered users:

SELECT * FROM users;

In the case of an SQL injection vulnerability, an attacker can exploit weaknesses in user input that are not controlled by the application. For example, if a web application allows users to enter their username without performing proper validation, an attacker could enter a malicious username that contains malicious SQL code. The resulting query might look like this:

SELECT * FROM users WHERE username = 'admin' OR '1'='1';

In the example above, the attacker injected the code 'OR '1'='1', which is an always true condition in SQL. As a result, the query will return all users in the database instead of just the user with the username "admin".

This simplified example illustrates how an SQL injection attack, but it can be much more complex and dangerous, can exploit a vulnerability to achieve unwanted results. It is critical that web applications properly validate and sanitize user input to prevent such attacks.

How to prevent SQL injection attacks?