What Is an SQL Injection? Is It Dangerous?

If there’s one thing cybercriminals love, it’s data. Stolen data is highly valuable on illicit marketplaces, and access to private databases can be a great way for malicious actors to make a profit from their ventures. One way to access private data is via an SQL injection. But what exactly is an SQL injection, how does it work, and can such an attack be prevented?

What Is an SQL Injection?

Software programs rely on code to function. Code is also the language that machines use to conduct operations, and can come in many forms (Python, JavaScript, C++, etc.). It is often through code that cybercriminals can attack victims, and SQL injections (or SQLis) are no different. These allow malicious actors to “inject” harmful code into an SQL statement.

Let’s first go over what SQL means.

SQL stands for Structured Query Language. This is another kind of programming language specifically used when dealing with databases. Developed in the 1970s by IBM, SQL can manipulate, store, and retrieve database information. Many database communication systems around the world use SQL, so it’s no surprise that threat actors have devised ways to abuse it in order to target databases.

SQL statements form a key part of database communication. An SQL statement is a command that comes in many different forms. Some alter data, some retrieve or delete it, and some can change the structure of the database itself. When an SQL injection occurs, the malicious code is injected into an SQL statement.

Of course, a website or application needs to be using the SQL programming language for an SQL injection to be possible. But how does this attack vector work?

Let’s say you have a regular line of code used by an application. When a cybercriminal inserts a malicious SQL injection, a line of code is added that can interfere with the queries the application itself makes sends to its database. By doing this, the database can be exploited in a way that allows the threat actor to view data that they would otherwise not have access to.

angled photo of code on screen

From here, the cybercriminal could steal data to exploit it directly or sell it on the dark web or elsewhere. They could also alter, add, or delete data from the targeted database. Depending on the degree of the SQL injection attack, a lot of damage could be done. If payment details, social security numbers, or other kinds of private data are accessed, many people could be at risk of being exploited.

On the other hand, if the attacker manages to significantly alter the database, large swathes of data could be permanently lost. All in all, SQL injections can destroy entire databases through just one attack. While they have been around since 1998, they are still relevant and dangerous in our current day.

As found by the Open Web Application Security Project (OWASP), 274,000 instances of SQL injections were identified when testing applications for the presence of such an attack in 2021.

The Types of SQL Injection

There are a few different kinds of SQL injection, with the main three being blind, in-band, and out-of-band injections.

A blind (or inferential) SQL injection occurs when the application or site is attacked by the injection, but the HTTP (Hypertext Transfer Protocol) responses provided don’t contain the result of the SQL query. In other words, no data from the database attacked is given to the cybercriminal. So, what’s the point of this?

Using a blind SQL injection, an attacker sends data to the target server and can then discern certain things about a database through the nature of the HTTP response itself. On top of this, factors associated with the HTTP response can help the attacker to create another, more effective SQL injection to access the database.

There are two key types of blind SQL injection, known as time-based and boolean. These two variants are quite similar in their nature. Both a boolean and time-based SQL injection sends an array of yes or no answer questions, though the latter will require the database to wait a short while before responding to the queries.

Next up, there are in-band SQL injections. In-band SQL injections allow the operator to carry out the attack and get the desired result using the same channel. In-band SQL injections are the most commonly used, simply because they’re the easiest to carry out due to the fact that they only require one channel.

Cables connected to the back of a rack-mounted server

Lastly, you’ve got an out-of-band SQL injection. This is essentially the alternate version of an in-band SQL injection, wherein the attacker cannot carry out the attack in total using one single channel. Alternatively, an attack may need to resort to an out-of-band SQL injection if the target server simply isn’t speedy enough to provide results.

These factors make the process a little more difficult, meaning it must rely on certain features to be active on the targeted database for success. For example, the platform being attacked must have a lack of input sanitization. Because of this, in-band SQL injections are far more common than out-of-band SQL injections. But they do still happen.

Can SQL Injections Be Avoided?

SQL injections are more of a concern for businesses and organizations than regular individuals. But there are things that these potential targets can do to lower the chance of being hit by such an attack.

Input sanitization is the key common practice for avoiding SQL injections. This is a filtering process that scans and cleans input of dangerous characters. If SQL code is processed before being sanitized, the chance of an SQL injection will naturally increase.

Additionally, parameterized queries can help you to steer clear of SQL injections. These are queries that require at least one parameter for execution. Applying parameters makes it harder for cybercriminals to successfully carry out an SQL injection attack.

But there is no surefire way to prevent an SQL injection. As is the case with many cyberattacks, it’s pretty much impossible to keep your devices and systems totally airtight. When it comes to SQL injections, the best you can do is sanitize all inputs and establish parameterized queries.

SQL Injections Are Aged, But Still a Threat

While SQL injections have been around for over 20 years, they still pose a risk to many websites and applications. So it’s a good idea to keep this form of attack in mind and take the necessary steps to try and prevent it, as it could pose a threat to your databases at some point in the future.

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