All Types of SQL Injection Attacks – Different Kinds of SQLi

When it comes to SQL injection attacks in SQL Server, users mainly know it’s a threat to their database, but they are not very aware of what the attack does. To protect the database from these types of cyber attacks, users need to be aware of every detail about the attack and SQL injection types, so that they can guard their databases more effectively. Let’s now examine the error in detail and understand the various types and their defenses. To learn more about the attack, it is important to understand what a SQL Query is and how this attack is associated with it.

An attacker with a false intention can counter authentication, access, manipulate, and delete crucial information in the DB. This article is going to address all the major & minor types of SQLi in depth. Moreover, we’re going to explain the entire topic to users with examples & ways to prevent such attacks. In a nutshell, users will get to know about these attacks & the defense mechanisms by reading this article till the end.

Understanding SQL Queries and SQL Injection Attacks

We all know that Structured Query Language (SQL) is a programming language used for accessing & manipulating data in a database. When the user or database administrator wishes to access or manipulate the data stored in these database management systems, they use SQL Queries like INSERT, SELECT, DELETE, etc. for the same. Working of SQL Databases depends on these queries as they help with the data modification, processing, and management.

SQL Injection attacks mean injecting or adding a malicious code/command to an existing SQL Query for unauthorized accessibility or manipulation. These attacks are carried out by understanding the vulnerability of existing SQL Queries. Here are some of the vulnerabilities in the SQL code to get an idea of how these attacks are done.

• Most applications often take user inputs directly and further insert them into the SQL query without validation, making the code vulnerable to being attacked. 
• When the database user uses concatenation (joining the SQL query with a value), it also gives the attackers a space to inject malicious code into.
• If the user has not set parameterized queries in SQL while running the queries, the user input is then considered as a SQL command. It also increases the risk of an attack. 
• The most obvious and common vulnerability for SQL Injection attacks is the weak authentication and authorization of the database. 

All these vulnerabilities give an opportunity to the users to attack the database and compromise the data of hundreds or thousands of users. Now, after we have a general idea of what SQL Injection attacks are and what kind of weaknesses allow the attackers to gain access to the data, let’s take a look at the SQL injection types to understand them better and find the appropriate defense against them. 

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Different Types of SQL Injection Attacks Explained

To understand these SQL injection attacks in a much better and precise way, we will now take a look at them thoroughly. There are three major SQL injection types.

• In-Band SQL Injection
• Inferential SQL Injection
• Out-of-Band SQL Injection

Let’s learn about them one by one, beginning with the first one.

In-Band SQL Injection or Classic SQLi

The In-Band SQL injection is the classic and most direct SQLi attack. This attack is known as the most direct attack, as the attacker uses the same medium to inject malicious queries and further retrieve the results. Elaborating more, this means, whatever the command the attacker injected in the query, the data or the leaked output will directly appear on the same website. Furthermore, the In-Band SQL injection attack type is divided into two parts:

• Error-Based SQL Injection Type:
  The Error-based SQL injection attack simply works by manipulating the database to generate and display error messages. These messages often reveal the internal details of the database. When the harmful SQL code is injected, the application might end up displaying the table names, column names, and other database objects, unintentionally. With these error messages, the attackers often get the idea of the crucial attributes within the database, further getting their hands on the information stored within. 
• Union-Based SQL Injection Type: Next, in types of SQL injection, we have union-based SQL Injection attack. In this type of attack, the attacker uses the SQL UNION operator. This operator helps merge two SELECT queries. Attackers mainly go for this attack when they need to get access to restricted or hidden data. This attack helps the attackers to fetch confidential information from the webpage, and can further lead to data theft and breaches.

Inferential SQL Injection or Blind SQLi Attack

This is another type of SQL Injection attack, but slightly different. In this attack, the data is not directly displayed to the attacker. The unauthorised users or attackers analyse the behaviour or pattern of the application for data extraction. This method for SQL data breach is slower than the other ones, but it is also more complex. As we can understand by the name, Blind SQLi, it indicates that the data isn’t directly attacked; however, it is retrieved through Yes or No questions from the database. This SQL injection types is also divided into two types:

Boolean-Based or Content-Based SQL Injection Type

In this SQL injection attack type, the attacker often sends the payloads that further lead to situations with True or False conditions. These situations can result in webpage changes or a no-change-at-all situation. Then the attackers observe whether the query injected has evaluated to a true or false value. In this attack, the entire process relies on a true or false type of query. 

Time-Based SQL Injection Attack

With this attack, the SQL injection manipulates the SQL functions that intentionally delay the operations. The attackers in this situation send queries like WAITFOR DELAY ‘00:00:07’ to check if the condition is true or not. In case the database pauses after the execution of the command, the attacker gets the idea that the condition is true; else, it didn’t pass. This attack works by using the time delays to confirm the conditions.

Also Read: SQL Data Error Cyclic Redundancy Check 23 Resolved

Out-of-Bound SQL Injection Attack

In this SQLi attack, when the attacker is unable to retrieve data using the channel through which they inject a malicious query. There can be several reasons for this, like unstable responses, disabled error messages, or strict firewall rules. However, the attackers retrieve the information by tricking the database into sending the information to an external source, like a DNS Server. 

So far, we have learned about the SQL injection types and how attackers get access to data using such commands. Now, it’s time to learn and understand the defensive steps that will allow users to protect their databases in a more secure and protected way.

Also Read: How to Patch SQL Server to Prevent These Attacks?

Protect SQL Databases Against SQL Injection Attacks!

Here are some of the best practices that will allow the users and database administrators to secure and protect their databases from such attacks. 

• Use of Parameterised Queries: These queries help users to separate the user inputs from SQL queries. Doing this ensures that the database uses the input only as data and not as executable code. 
• Use Stored Procedures: The stored procedures in SQL Server add a layer of control between the database and the application. These stored procedures, when written correctly, restrict the attackers from injecting any malicious code. 
• Apply Least Privilege Access for Security: Another practice to safeguard the database is to allow limited permissions to users to operate the database. With permission limitations and access restrictions, the risk of SQL injection attacks minimises. 
• Disable the Error Messages: Error messages become a crucial part in SQLi attacks. By disabling the error messages in SQL databases, it becomes more complex and challenging for users to know about the details of the database. 
• Update SQL Server Software: Users can protect the database by keeping the SQL software and frameworks updated. This helps them protect the database with better security features.

Conclusion

Finally, we hope that users are well aware of different types of SQL injection attacks in depth. Moreover, we expect that users are capable enough to protect their database from such critical attacks. Moving ahead, the advanced tool is the perfect solution for users to safeguard the entire database from SQL attacks.