How Do SQL Injection Attacks Work and How to Prevent Them?

What Is SQL Injection?


SQL injection (SQLi) is a type of cyberattack against web applications that use SQL databases such as IBM Db2, Oracle, MySQL, and MariaDB. As the name suggests, the attack involves the injection of malicious SQL statements to interfere with the queries sent by a web application to its database.

Here is how a web application normally works. A user first enters their login credentials into the login form. After these credentials are successfully authenticated, the web application would send an SQL statement in the form of a query to the hosting database to bring forward the user’s data stored in that database. From this user’s perspective, they would now be able to access their account information and send further queries to the database for every action and change made within their account.

Now, when a SQL injection vulnerability exists, an unauthorized threat actor could somehow skip the authentication process and manually inject SQL statements to send fraudulent queries to the database. This would allow the attacker to view, modify, and delete data from the database.

SQL injection is not only highly common, but also very dangerous as it can lead to unauthorized access to personal data, financial information, intellectual property, and trade secrets. It has been listed as the number one risk on the OWASP top 10 list of web application security threats. A large number of data breaches were the result of SQL injection attacks.


How Does a SQL Injection Attack Work?


A SQL injection attack targets vulnerabilities in dynamic SQL statements. Think of a dynamic SQL statement like a multivariate function in mathematics, of which the parameters are fixed, while the values substituted in the independent variables determine the result. 

Similarly, a dynamic SQL statement also consists of a predetermined set of parameters (such as a web form), of which the complete statement is only generated when a user fills in their inputs. See the following example of a SQL statement of a login form:

SELECT * FROM users WHERE username = ‘$username’ AND password = bcrypt (‘$password’)

After the user enters their username and password, the statement would be completed, after which a query would be sent to the server to retrieve the user’s information from the database.

When a vulnerability exists in a dynamic SQL statement, the attacker would be able to enter complex scripts into the forms to interfere with the preexisting parameters to alter the meaning of the complete statement.


How to Prevent a SQL Injection Attack?


Technically, the only way to prevent a SQL injection attack is to have input validation in place. This means that inputs entered by the users must be monitored and sanitized to filter out any potential malicious codes.

This is exactly what a web application firewall (WAF) does. It analyzes all inputs entered by the users into the web application to find any matches with suspicious codes.


WAPPLES, the Best Defence Against SQLi

Penta Security’s WAPPLES is a web application firewall that logically detects malicious scripts from web application traffic. Its rule-based detection engine allows for maximum efficiency without compromising application performance.

With the No.1 market share in the Asia Pacific region, WAPPLES is the best solution against all types of SQL injection attacks.

To learn more about WAPPLES, click here.


Check out Penta Security’s product lines:

Web Application Firewall: WAPPLES

Database Encryption: D’Amo

Identity and Access Management: ISign+ 

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