How to Prevent SQL Injection Attacks: Key Techniques To Protect Your Online Presence

Most modern applications and websites refer to databases that are written in Structured Query Language (SQL), which fetches and alters the information with normal commands such as “SELECT,” “UPDATE,” “INSERT,” “CREATE,” “DELETE,” and “DROP.”

But when sites do not properly screen, filter, or manage their queries, SQL injection (SQLi) attacks take place. According to Statista reports, SQL injection is the most significant source of web application critical vulnerabilities (23.4%) discovered worldwide in 2023. This serves to underscore the importance of carefully understanding the intricacies of SQL injection attacks and their preventive strategies.

Here, you’ll have a precise understanding of what an SQL injection attack is, how it is caused, its effect on security, and how to prevent SQL injection attacks.

Defining an SQL Injection Attack

An SQL injection attack is a form of web application attack in which the attacker “injects” malicious SQL commands into SQL statements in order to view or alter application data. Such exploits make use of places in online applications where the user is prompted for input, thereby enabling the attacker to execute the database in ways that are not intended.

Some of the most notorious SQL injection attacks include:

• 2012 LinkedIn data breach: Nearly 170 million credentials were compromised
• 2012 Yahoo hack: 453,000 email credentials of Yahoo Voices users were leaked
• 2018 Quora data breach: 100 million Quora users’ data were exposed
• 7-Eleven retail store breach: 130 million credit card numbers were stolen

What Causes SQL Injection?

The root cause of SQL injection in most instances is incorrect user input sanitisation. Attackers are able to inject malicious SQL queries if an application receives user input in SQL statements without proper validation.

Typically, attackers have means to take advantage of vulnerabilities that cannot differentiate between trusted and untrusted code. Next, they design and implement the malicious query by bypassing security controls, followed by database and server extraction and manipulation.

For example, a simple SQL query using a SELECT statement to check user login credentials against the users table could be:

If the given username and password combination already exists, this will return a valid user ID, otherwise NULL (an empty result). However, if the code directly inserts raw user inputs into the query, it is probably susceptible to SQL injection.

Impact of an SQL Injection Attack

Before understanding how to prevent SQL injection attacks, you might be wondering how an SQL injection attack can damage your website or web application. Let’s consider some serious consequences.

1. Stolen data: Attackers can retrieve private data from a database, including credit card numbers, usernames, passwords, and personal information, pretend to be the real users, and enjoy their access privileges.
2. Database takeover: SQLi attacks let attackers gain complete access to data stored on a database server and carry out more harmful actions such as virus installation, further attacks, or unauthorised modifications.
3. Data alteration or deletion: Attackers can add misleading transactions, manipulate existing records, delete records from a database, or even drop entire tables, thus affecting data integrity.
4. Lateral movement: By gaining operating system rights on database servers, attackers can get access to other sensitive systems.

Due to the above activities, your company can suffer immense financial loss, such as system restoration and data recovery fees, lost sales as a result of interference, fines, legal liabilities for data breaches, and damage to reputation in the long run.

In order to prevent or minimise the above effect of SQL injection attacks, you should be well-familiar with some techniques. Let’s talk about them next.

How to Prevent SQL Injection Attacks: Effective Techniques

It is crucial to secure all inputs and server-side activities to successfully prevent SQL injection attacks. While client-side validation is useful, it is insufficient to stop determined attackers. Here’s a thorough strategy that includes essential preventive measures to combat SQL injection attacks.

Validate and Sanitise User Input

To ensure that the user input conforms to predefined specifications, such as format, length, and range, use input validation. Moreover, to remove or encode potentially malicious characters from the input, incorporate input sanitisation.

In order to offer maximum security, validate user input both on your application’s server side and client side.

Use Escaping for User Input

You may also use escaping, which involves modifying user inputs to neutralise special characters that could be used for malicious SQL injection. By doing so, the database comprehends them as literal values instead of executable code (commands or conditionals).

The Open Worldwide Application Security Project (OWASP) offers the Enterprise Security API (ESAPI), a free and open source tool to help you implement escaping in legacy database code.

Utilise Prepared Statements with Parameterised Queries

By separating user inputs from the SQL query, parameterised statements do away with the necessity for manual escaping. This stops malicious code from running by guaranteeing that user inputs are handled as data. During execution, the database securely binds user inputs and detects placeholders.

When an attacker includes a malicious string, a prepared statement treats it as a literal value. This means that the query will search for an exact match for the string, and if no such match exists, it will fail.

Leverage Stored Procedures

Similar to prepared statements, stored procedures only differ in that the SQL code for the stored procedure is defined and kept in the database rather than in the user’s code. The application will activate stored procedures and return the results rather than running code directly on the database.

Conduct Continuous Scanning and Security Audits

Frequent code reviews and security audits involve in-depth analyses of the application’s codebase. Incorporate both automated tools and manual inspections to better locate and resolve possible vulnerabilities, and hence ensure continued security. Also keep your software and frameworks up-to-date to patch known vulnerabilities.

Deploy Web Application Firewalls (WAF)

A software or appliance-based web application firewall (WAF) helps filter out incoming HTTP traffic, detecting and blocking SQL injection attempts and other dangerous activity.

Common techniques include:

• Pattern matching, which is identifying typical SQL injection signatures by comparing incoming requests to a set of established rules
• Deep packet inspection to examine request content and make sure that only valid traffic is permitted

Use Whitelists Instead Of Blacklists

Do not use blacklists to filter user input since its easier for a cunning attacker to figure out how to get around your blacklist. Instead, use stringent whitelists only to validate and filter user input, if possible.

For instance, you can ask your developer to filter and accept only the required “@” character and other characters found in an email address.

Follow the Least Privilege Principle

The idea behind least-privilege access is to grant users only the required access to protected resources. It reduces the impact of a breach since hackers who use stolen credentials to access a database will have restricted access to protected data, making it harder for them to alter, steal, or delete it.

How To Prevent SQL Injection Attacks with Crazy Domains

Securing your online presence against SQL injection attacks is important in today’s digital age. With knowledge of how to prevent SQL injection attacks and leveraging the expertise and resources provided by Crazy Domains, you can make your online experience safe and successful.

Crazy Domains provides fast, scalable, and secure hosting with regular updates and monitoring, along with tools and plugins to enhance your site’s security without spending a fortune.

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