All Types of SQL Injection Attacks – Different Kinds of SQLi

SQL injection or SQLi is an attack that injects the target’s database with malicious SQL code for backend database manipulation. There are different types of SQL injection attacks present at the moment. Nowadays, SQLi attacks are getting common day by day with a 95% growth rate from the previous year. Yes, it is quite dangerous & users are still not well aware of all kinds of SQL injection attacks.

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 errors. In a nutshell, users will get to know about these attacks & the defense mechanisms by reading this article till the end.

Understanding A SQL Query

We all know that Structured Query Language is a programming language used for accessing & manipulating data in a database. MS SQL Server, MySQL, etc, database management systems use this language. Now, a user executes a query using this language which in return provides results to the users. There can be several elements in a query like SELECT, DROP, INSERT, etc.

Let’s understand types of SQL injection attacks with an example of an e-commerce website’s database:

SELECT ItemName, ItemDescription
FROM Item
WHERE ItemNumber = ItemNumber

After this, the web-based app generates a STRING query and sends this to the database as a single statement for the result. It looks like this:

sql_query= "
SELECT ItemName, ItemDescription
FROM Item
WHERE ItemNumber = " & Request.QueryString("ItemID")

Now, the user enters the input to get the desired results:

SELECT ItemName, ItemDescription
FROM Item
WHERE ItemNumber = 001

Finally, as a result, the SQL Database will provide the results for item number 001 to the user. 

This is a particular query example. Let’s understand the types of attacks to see how it affects the database.

Also Read: How to Repair LDF File with Ease?

Different Types of SQL Injection Attacks

To let users understand all kinds of SQL injection attacks, we have divided these in certain categories. Putting it simply, we have three primary categories named as In-band SQLi, Inferential SQLi, and Out-of-band SQLi. However, there are further sub-categories within these.

Without any further ado, let’s quickly find out about these SQLi types in depth starting with the classic ones towards the modern ones.

In-Band SQLi or the Classic SQLi

As mentioned, In-Band or classic SQLi is one of the oldest as well as common common attacks on SQL Servers. Here, the attacker uses a single communication channel for both tasks of launching the attack & gathering the results. It is quite simple to execute different types of SQL injection attacks. This is why it’s used all over the world. Furthermore, we have two sub-categories in this mentioned below:

Error Based SQLi

From different kinds of SQL injection attacks, when an attacker purposefully penetrates the database with malicious SQL queries, the system often gives output in the form of errors. Now, these SQL Server errors can reveal a lot about the database structure, table names, views, & other elements.

As the attack gathers information using the error outputs, the name of this category is error-based. Later on, using the information gathered, attackers create more precise SQL queries to get more data from the database. Therefore, the process gets going till the attacker is satisfied or there is a major barrier.

Union Based SQLi

Users must be aware that a Union SQL operator helps combine the data gathered as a result of multiple SELECT queries. An attacker uses this way to attack by getting data from such crucial parts of the database not intended to be accessed by everyone. This type of SQL injection attack here consists of four steps as mentioned:

1. Identify Vulnerable Points
2. Test for Union Feasibility
3. Inject malicious SQL Query
4. Extract the Data for Misuse

Inferential SQLi Also Known as Blind SQLi

Here comes the second major category of the SQLi. the reason we call it blind is because here the attacker can not find out the result of the ongoing attack. It’s like a game of cards when a player bets blind just by intuition.

To be precise, an attacker of the Blind SQLi simply attacks the SQL database & instead of getting information, the attacker sends payloads to reconstruct the database based on the response or the behavior of the database after the last query.

Here also, we have two sub-categories to have a look at:

Boolean-Based or Content-Based SQLi

This is a game of true or false in simple words. Here, the attacker sends the SQL query to the database that puts the application in a situation where it has to result in a different value using the True or False manner.

Here, based on the result, the HTTP content might change or remain unchanged. This way, an attacker can understand if the payload sent resulted in a positive or negative. All of this happens without any data returned from the SQL Server. Also, we must note that this process is slow &the attacker need to work hard for getting the desired information.

Time-based SQLi

When an attacker sends SQL query to the database with a condition to wait for a while before responding, it’s known as Time-based SQLi. The response time here acts as the indication for the user as True or False.

Here, depending on the result, either the HTTP response will return at the moment or after a certain delay. It is similar to Boolean-based but with one difference of time constraint.

Also Read: SQL Data Error Cyclic Redundancy Check 23 Resolved

Out-of-Band SQLi

Among all types of SQL injection attacks, here we have the final one as Out-of-Band SQLi. This attack is not very common. Not because it is hard or new. The reason for this attack being rare is that the database must be enabled with certain features to execute this one. Therefore, this attack can not target all the SQL Servers. When an attacker can not use the same channel for launching the attack & gathering results, they prefer the Out-of-Band method.

In cases where the server responses aren’t stable, the Out-of-Band attack allows users the alternative to inferential time-based techniques. This method relies on the server’s ability to provide the attacker with information using the DNS & HTTP response.

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

Prevent Different Types of SQL Injection Attacks with Example?

There can be various steps that users need to take to prevent such attacks. However, all of them fail at some point. Evidently, trusting the classic solution of MDF, LDF & LDF backup is the best way.

Users must opt for the SQL Server Recovery Manager for such incidents which can easily help users get the desired solution. This one solution combines several different solutions that can recover MDF, LDF, and NDF files, repair the damages in files, get back deleted data, etc. Download the solution now to stop SQLi and fix plenty of issues including index corruption in SQL Server as well.

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.