What is an SQL Injection Attack? Full 2024 Guide

Sam Boyd
Updated on: August 22, 2024 Chief Editor

SQL is a programming language that allows programmers to “talk” to large databases using nearly-plain English. It can access and manipulate data held in a number of tables on a server. When it comes to websites, those tables might include sensitive information like usernames, passwords, credit card numbers, and more.

The problem is, websites can sometimes be tricked into running malicious SQL queries when proper precautions aren’t in place. This kind of attack is called SQL injection (SQLi), and in this guide, we’ll explain how it works and how to prevent it on your website in 2024.

One of the best ways to prevent SQL injections is by having business-grade antivirus protection. Enterprise antivirus solutions provide an additional layer of protection against SQL injection attacks and often include features like web application firewalls (WAFs) and intrusion detection systems (IDS) that monitor and analyze incoming traffic for malicious SQL queries.

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What Is an SQL Injection Attack and How Do They Work?

Most large websites or web apps will usually have at least one interactive area where the content changes based on a user’s input. Examples might be:

• Ecommerce sites that populate products based on a search query.
• Membership sites that ask for a username and password.
• Review sites that allow user-submitted content.

When the server receives these inputs, it then translates the entry into a simple SQL query to retrieve and display the right data.

In other cases, a server may create a query to check the input against data from a table (like username and password) or add data to a table for storage (like a new user review for a product).

On a website without proper protections in place, hackers can make modifications to their inputs to form malicious queries that create disastrous consequences. For example, they may add partial elements of SQL queries to the username field to trick the database into displaying, manipulating, or deleting critical data that only admins should have access to.

If their efforts are not impeded, a hacker could:

• Determine if the website’s database has a vulnerability.
• Discover the name of data stored on the database.
• Find the individual data columns in a given table (username, password, credit card number, and more).
• Delete, manipulate, or display that confidential data.

SQL Injection attacks have been prevalent for over a decade. They are well-known in the cyber security industry, and most major web companies have gone to extreme lengths to sniff out vulnerabilities. WordPress, for example, which powers about 30% of the entire internet, is constantly patching vulnerabilities with every new version.

There have been fewer documented cases of successful attacks in recent years, but website owners and database managers need to stay on top of best practices when it comes to web security.

Types of SQL Injections

• In-band SQL injection. This is the simplest and most common form of SQLi attack. During in-band attacks, hackers can see the results of their queries on the same screen as their input (for example, on a product search page). They can use the data to gather the information they need about the database and then construct a query to display, delete, or manipulate certain data.
• Blind SQL injection. In a blind SQL injection, the hacker doesn’t necessarily see the results of the queries run via their inputs, but they can slowly piece together information based on failed pages, response times, and other subtle pieces of data that appear over the course of several queries.
• Out-of-band SQL injection. When clues from blind SQL injections are too hard to read, attackers can sometimes force the database to send a DNS request to their own site. If the DNS request comes through on the other end, it gives hackers more information about potential vulnerabilities they can use to further their attack.

How to Prevent SQL Injection Attacks

• Run frequent updates. If you’re using a popular content management system, update it frequently. Also, update your versions of PHP, MySQL, and anything else that might connect to your database.
• Restrict and sanitize inputs. Good input fields won’t run a query unless the input specifically matches your requirements. This is called restricting your inputs. For example, ensure usernames in login fields are only letters and numbers without special characters. You can also add functionality to user inputs that recognizes dangerous characters, rendering them harmless.
• Store sensitive data securely. Your database should never store user passwords as plain text. At a bare minimum, passwords should be hashed using the toughest algorithms. Better yet, you should have a system that appends a random string of characters to each password before hashing it. Failing to securely store sensitive data can be a crime in some cases.
• Use prepared statements, parameterized queries, and PHP data objects. Ensure that SQL elements in a user input field aren’t treated as actual queries. For example, if you use a prepared statement or parameterized query, the server knows what command to expect. In this case, the query can’t be altered outside of the input variables. More recent PHP versions let you categorize user inputs as PHP Data Objects (PDOs). This is a very simple way to make sure that the server only reads input as data and ignores any commands.
• Do not display specific error messages to users. Hackers can gleam a lot of information from the errors that result from failed queries. If anything, you’ll want to display only the most generic error message possible for all failures. It’s a good idea, however, to keep a server-side log of all errors and failed requests so you can review them later in the case of an attack.
• Use a scanner to detect SQL Vulnerabilities. There are lots of free and paid tools that will scan your website or app for vulnerabilities. They’ll search for known weaknesses in your platform and test different kinds of SQL injection attacks on your site. It’s better to know now and fix the problem then find out too late!
• Use a WAF firewall. A Web Application Firewall (WAF) acts as a barrier between your web application and the internet, filtering out malicious traffic before it reaches your server. By analyzing incoming HTTP requests, a WAF can detect and block SQL injection attempts and other web-based attacks. This helps to protect your database and sensitive information from being compromised.
• Use an enterprise-grade antivirus. Enterprise-grade antivirus solutions offer strong security features designed to protect your web applications and databases from various threats, including SQL injection attacks. These solutions often include real-time monitoring, threat detection, and advanced heuristics to identify and block malicious activities. Implementing an enterprise-grade antivirus adds an essential layer of defense to protect your website and data.

In 2024, SQL injection attacks should be relatively easy to avoid if you’re relying on modern and trusted technology. However, the best practices above will help you be aware of potential vulnerabilities. Protections are relatively easy to implement, but one slip-up could have disastrous consequences for your business, customers, or website.

How to Recover From an SQL Injection Attack

If you’ve fallen victim to an SQL attack, you need to act quickly to prevent damage to your website, or worse. Follow these steps:

• Shut down the website. Immediately take your website offline to prevent further damage and unauthorized access. This helps to contain the breach and minimizes the risk of additional data being compromised.
• Discover what codes have been affected. Conduct a thorough investigation to identify the malicious code and determine which parts of your database have been compromised. Analyze server logs and use security tools to trace the source of the attack and the extent of the damage.
• Replace the strings of the affected table. Carefully replace or repair any corrupted data or code in the affected database tables. Ensure that you restore data from clean backups to maintain the integrity of your information.
• Test it. Rigorously test your website and database to ensure that all vulnerabilities have been addressed and no residual malicious code remains. Perform multiple security checks and penetration tests to verify the effectiveness of your remediation efforts.
• Put stronger protections in place. Enhance your security measures by implementing stronger input validation, using prepared statements and parameterized queries, and deploying a web application firewall (WAF). Regularly update your software and conduct routine security audits to prevent future attacks.
• Bring your website back online when you’re sure the tables are foolproof. Once you are confident that your website is secure and all vulnerabilities have been addressed, bring it back online. Monitor the site closely for any signs of unusual activity and continue to refine your security protocols.
• Notify affected parties and comply with legal requirements. Inform your users and stakeholders about the breach and the steps you’ve taken to mitigate the issue. Ensure you comply with any legal obligations, such as data breach notification laws, to maintain transparency and trust.

By following these steps, you can effectively recover from an SQL attack and strengthen your website’s defenses against future threats.

Frequently Asked Questions

How can an antivirus protect my website from SQL injection attacks?

An antivirus can protect your website from SQL injection attack by using advanced features such as web application firewalls (WAF) and intrusion detection systems (IDS). These tools monitor and analyze incoming traffic for malicious SQL queries, blocking them before they can reach your database. Additionally, real-time threat detection helps identify and neutralize potential vulnerabilities, adding an essential layer of security to your website.

What are some common signs that my website has been attacked with SQL injection?

Common signs of an SQL injection attack include unusual database behavior, such as unauthorized access to data, unexpected changes to the database, frequent error messages, and data corruption. Other indicators include a sudden drop in website performance, unexpected pop-ups, and abnormal spikes in network activity. Regular monitoring and security audits can help detect these signs early and mitigate the damage. If you spot any of the signs, you should take the steps to recover from an SQL attack.

Why is input validation important in preventing SQL injection?

Input validation is crucial in preventing SQL injection because it ensures that only correctly formatted and expected data is accepted by your database. By validating and sanitizing user inputs, you block malicious code from being executed within your SQL queries. This reduces the risk of unauthorized access and manipulation of your database, maintaining the integrity and security of your data.