Data is an essential component of technology. Amidst technological advancement, people create and use a large amount of data.

On average, 2.5 Quintilian bytes data per day was generated in the year 2020

(Source: Domo)

Online, such huge data is stored under databases. In recent years, databases that are part of web applications are facing several security issues and threats, such as unauthorized access.

Web applications make organizations public via the Internet, and that makes them vulnerable to Web-based attacks. Among such attacks persists SQL injection, which possesses a serious threat to the organization’s cybersecurity.

In this article, we will explore SQL injection attacks in detail and get answers to the following questions:

• What is a SQL injection (SQLi) attack?
• What are the different types of SQL injection attacks?
• How does SQL Injection attack affect web applications?
• How to prevent your web application from SQL injection attacks?

What is SQL Injection (SQLi) Attack?

SQL Injection attack is one of the most common web application vulnerabilities. SQL Injection attack method executes malicious SQL queries that control a database server from the backend and exploit security vulnerabilities in the database of web applications. Hackers can gain unauthorized access to the database and extract sensitive information by using injections.

A general structure of SQL query is:

  SELECT column1, column2 

  FROM table1, table2 

  WHERE column2='value';

Once hackers bypass application security measures by exploiting SQL Injection vulnerabilities, they become capable of adding, modifying, and deleting data from the database.

SQL Injection attacks can affect a web application that uses SQL databases, such as MySQL, Oracle, SQL Server, etc.

Different types of SQL Injection Attacks

Generally, SQL injections attacks come under three categories:

• In-band SQLi (Classic)
• Inferential SQLi (Blind)
• Out-of-band SQLi

In-band SQLi 

In this type of SQL Injection attack, the hacker manages to use the same communication channel for launching attacks and assembling results. 

This infamous SQL Injection attack has two subunits:

Error-based SQL Injection: 

In this method, the attacker deliberately causes the error messages to pop up for determining the system vulnerabilities and returning full query results to reveal all the confidential information from the database structure.

Union-based SQL Injection:

This method uses the SQL UNION operator that blends multiple SQL query statements to obtain the single HTTP response. This can allow the attacker to extract the information.

Inferential SQLi 

In this technique, an attacker sends out the data payloads to the server in order to observe the web application’s response and results so that they can recreate the database structure.

The types of inferential SQLi includes: 

Boolean:

This technique depends on sending an SQL query to the database to gather a result from the application server. In this attack, the server returns a true or false message. However, it is a slow attack, and no data can be recovered in this attack.

Time-based:

The attacker determines the true or false result by waiting for the response from the server and analyzing the time taken by the database to respond.

Out-of-band SQLi

This is the least popular SQL server attack approach, which includes specific SQL-enabled database features. In this attack, DNS or HTTP query is submitted to the SQL server that contains a SQL statement. On successful submission, attackers can perform various actions, such as sending database information, mitigate user privileges, and many more.

Effect of SQL Injection

SQL injection attacks target the database of the web applications by using the SQL statements to deceive the system into delivering some uncalled or undesired tasks. 

The SQL injection attack can cause various damage to the application, such as:

• Modify, alter, or delete the data from the database
• Gaining unauthorized access and retrieving sensitive/confidential information
• Extracting the database content of a specific file
• Executing malicious administrative tasks such as locking the application database.
• Identify the user details and use them on cyber-attacks on other sites.
• In worst cases, take over the entire database and web application.

Defense Against SQL Injection Attacks

The developers, system administrators, and database administrators in the organization can take the following safety measures to secure your application database and mitigate SQL injection attacks.

• Make sure that all the web application software components are updated with the latest security patches or updates without leaving any place for vulnerabilities. 
• Try not to use the shared database accounts among various web applications or sites.
• Monitor the SQL statements from the web applications to identify any vulnerabilities.
• Discard any database functionality, which is no longer in use so that it can be prevented from being misused by hackers and limit the area for the SQL attack. 
• Ensure that you are displaying minimum information and error messages to prevent Error-based SQL injection attacks.
• Keep the database credentials encrypted and separated securely.

In the End

If you want to know more about SQL injection threats and other web attacks and their prevention methods. Pursue the Cyber Security Course by Krademy!