· Alex · security  · 9 min read

How to Test for SQL Injection

Types of SQL injections, testing tools and methodology

Types of SQL injections, testing tools and methodology

How to Test for SQL Injection

How SQL injection works

The root cause of SQL injection is not properly sanitizing user input. So, when an application takes in data from users without checking or cleaning it, that’s when things can get ugly. Attackers can input malicious SQL code that gets executed by the database, and that’s when they can start wreaking havoc.

Manipulation of SQL queries

The real power of SQL injection comes from the ability to manipulate SQL queries. By inserting harmful SQL code, attackers can change the intended behavior of the query. This lets them access, modify, or even delete data in the database, all without permission. Not cool, right?

Types of SQL injection attacks

There are a few different types of attacks that you should be aware of:

  1. In-band SQL injection

In-band SQL injection is the most common type, and it’s all about using the same communication channel for injecting the malicious SQL code and getting the results. This means that the attacker can see the outcome of their handiwork right away.

  1. Blind SQL injection

Sometimes, the application doesn’t show the results of an injected query, making things a bit trickier for the attacker. But don’t underestimate their determination! In blind SQL injection, attackers send a series of true or false questions to the database and observe the app’s responses. They can then piece together the info they want.

  1. Out-of-band SQL injection

Out-of-band SQL injection is less common, but it’s still worth knowing about. This type of attack involves using a different channel (like email or DNS) to send and receive data. It’s often used when in-band and blind SQL injection techniques don’t work, and it requires certain conditions to be met, like the attacker being able to control the server’s DNS.

Impact of SQL injection attacks

SQL injection attacks can cause some serious damage. Here’s a breakdown of the potential fallout:

  1. Data theft
  2. Data modification
  3. Loss of confidentiality and integrity
  4. Damage to reputation and legal consequences

SQL Injection Testing Tools

Let’s talk about the tools we can use to test for SQL injection vulnerabilities. There are two types of tools: automated and manual. Let’s dive into each category and see what’s available.

Automated tools

Automated tools can help you find SQL injection vulnerabilities with minimal effort, which is pretty sweet. Here are some of the most popular ones:

  1. SQLMap

SQLMap is an open-source tool that automates the process of detecting and exploiting SQL injection vulnerabilities. It supports a wide range of databases and can even crack hashed passwords! It’s pretty awesome and simple to use, making it a go-to for many security pros.

  1. Havij

Havij is another popular automated tool designed specifically for SQL injection. It’s super user-friendly, with a nice graphical interface that makes testing a breeze. Just plug in the URL, and it’ll do the rest. Keep in mind that it’s not open-source, so you’ll need to buy a license to use it.

  1. jSQL Injection

jSQL Injection is a Java-based tool that can be used on Windows, Mac, and Linux. It’s got a clean interface and supports a bunch of databases, including MySQL, Oracle, and PostgreSQL. Plus, it’s open-source, which is always a plus.

  1. SQLninja

SQLninja is tailored for exploiting SQL injection vulnerabilities on web apps that use Microsoft SQL Server. It’s got a bunch of nifty features, like the ability to gain remote access and execute commands on the target server. However, it’s a bit more advanced, so it might not be the best choice for beginners.

Manual tools

Sometimes, automated tools don’t catch everything, so you’ll need to roll up your sleeves and do some manual testing. Here are a couple of useful tools to help you out:

  1. Burp Suite

Burp Suite is a fantastic web application security testing tool. It’s got a ton of features and it also supports extensions.

  1. OWASP Zed Attack Proxy (ZAP)

ZAP is another excellent tool developed by the Open Web Application Security Project (OWASP). It’s open-source and has a bunch of features for manual testing, including the ability to intercept and modify HTTP requests. This makes it great for spotting and exploiting SQL injection vulnerabilities.

Pros and cons of each tool

Every tool has its own set of pros and cons, so let’s break it down:

  • Automated tools are super convenient and can save you a ton of time. However, they might not catch every vulnerability, especially if the attack vector is complex or unique.
  • Manual tools give you more control and can help you find vulnerabilities that automated tools miss. On the flip side, they can be more time-consuming and require a deeper understanding of SQL injection techniques.

So, which tool should you choose? It really depends on your skill level, the specific application you’re testing, and how thorough you want to be. A good approach is to use a mix of automated and manual tools to make sure you’re covering all your bases.

Preparation for SQL Injection Testing

Identifying potential targets

First things first, you need to figure out where the potential vulnerabilities might be hiding. Here are some common places to look:

  1. User input forms

Any form that accepts user input is a potential target for SQL injection attacks. This includes login forms, registration pages, search bars, and more. Basically, if it takes user input, keep an eye on it!

  1. URL parameters

URL parameters are another juicy target for attackers. They can be manipulated to inject malicious SQL queries, so make sure to scrutinize them closely.

  1. Cookies and HTTP headers

Attackers can also exploit cookies and HTTP headers to carry out SQL injection attacks. While these are less common targets, it’s still important to check them out, just in case.

Before you start testing, make sure you have permission to do so! If you’re testing someone else’s application or website, always get written consent. It’s better to be safe than sorry, and you definitely don’t want to end up in legal hot water.

Manual SQL Injection Testing Techniques

Basic injection techniques

Starting with the basics, here are three common techniques used in manual SQL injection testing:

  1. Tautologies

Tautologies are statements that are always true. In SQL injection testing, they’re used to bypass authentication mechanisms, like login forms. By injecting a tautology, you can trick the application into thinking the injected query is valid, granting you access.

  1. Union-based injections

Union-based injections involve using the SQL UNION operator to combine the results of two or more SELECT statements. This allows you to retrieve additional data from the database that you wouldn’t normally have access to. Just make sure the number of columns in each SELECT statement is the same!

  1. Error-based injections

Error-based injections rely on deliberately causing an error in the SQL query. By doing so, you can extract valuable information from the error messages that the database returns.

Advanced injection techniques

Let’s move on to some more advanced techniques:

  1. Time-based blind SQL injection

In time-based blind SQL injection, you inject a query that causes the database to wait for a specified amount of time before responding (for example, using SLEEP command). By observing the response time, you can infer whether the injected query was true or false. It’s a bit slower than other techniques but can be very powerful.

  1. Boolean-based blind SQL injection

Boolean-based blind SQL injection is all about asking the database true or false questions. By injecting a query that returns a true or false result, you can slowly gather information about the database.

  1. Out-of-band exploitation

As we mentioned earlier, out-of-band exploitation involves using a different channel (like email or DNS) to send and receive data. This technique is less common and requires specific conditions to work, but it can be useful when other techniques aren’t getting the job done.

Tips for effective manual testing

Now that you’re familiar with the techniques, here are some tips to help you nail your manual SQL injection testing:

  • Always test both single and double quotes in your injections, as different databases have different behaviors.
  • Be thorough and methodical. It’s easy to miss vulnerabilities if you’re rushing through the testing process.
  • Keep track of your findings as you go. This will make it easier to analyze and remediate vulnerabilities later.
  • Don’t rely solely on manual testing. Combine it with automated testing to ensure you’re covering all your bases.

Automated SQL Injection Testing

Automated tools can be a real time-saver and help you catch vulnerabilities you might’ve missed. So, let’s dive into how to configure and use them, as well as their limitations.

Configuring and using automated tools

Automated SQL injection testing tools usually come with a bunch of options to help you tailor your tests. Here’s a quick rundown:

  1. Scanning options

Most automated tools allow you to choose which parts of the application to scan. This could include user input forms, URL parameters, cookies, and more. Make sure to configure the tool to cover all the potential targets you identified during the preparation phase.

  1. Attack options

Automated tools often have options to choose the types of attacks to perform. This might include error-based, union-based, or blind SQL injection attacks, among others. You’ll want to select the most appropriate attack options based on your application’s architecture and the specific vulnerabilities you’re looking for.

Limitations of automated testing

Automated tools are great, but they’re not perfect. Here are some of the limitations you should be aware of:

  • Automated tools might not catch every vulnerability, especially if the attack vector is complex or unique.
  • They can produce false positives or false negatives, leading to wasted time or overlooked vulnerabilities.
  • Some tools may have a limited understanding of custom code or unique application logic, which can affect the accuracy of the results.


SQL injection attacks can have serious consequences for your application, your users, and your organization as a whole. It’s crucial to perform thorough testing to identify and address vulnerabilities before they can be exploited by malicious actors. Don’t skimp on the testing, and always be on the lookout for new vulnerabilities. Both manual and automated testing have their strengths and weaknesses, and the most effective approach to SQL injection testing is to strike a balance between the two. By combining the precision and flexibility of manual testing with the speed and efficiency of automated testing, you’ll be better equipped to catch vulnerabilities and keep your application secure.

About the Author:


Application Security Engineer and Red-Teamer. Over 15 years of experience in Application Security, Software Engineering and Offensive Security. OSCE3 & OSCP Certified. CTF nerd.

Back to Blog

Related Posts

View All Posts »