Web Application Penetration Testing Tutorial For Beginners

What is SQL Injection (SQLi) Attack in Website & Web Application? Explained

Meaning of SQL Injection or SQLi Attack

SQL injection or SQLi is a prevalent attack vector where the malicious SQL code is executed to tamper or compromise the backend database. SQL injections make confidential information and data accessible, which was not supposed to be displayed. 

The data exposed through SQLi can be the sensitive information of an organization, users, customer data, etc.

These attacks can hamper the credibility of a business, as well as cause the deletion of important data. Sometimes, the attackers can also find admin access to the database, which can cause big losses.

Test your knowledge with a quick quiz!

In SQL Injection, which code is inserted into strings that are then passed to an SQL Server instance?

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Types of SQL Injections Attacks

There are three types of SQL injections, as defined below:

1. In-band SQLi

In this type of SQL injection attack, the channel of interaction for carrying out attacks is also used for collecting the information. This is an easy-to-launch and efficient attack, which makes it too prevalent. 

The in-band SQL injections have two sub-variations, which include error-based SQLi and union-based SQLi. 

If the launched attack makes the database show error messages, it is called error-based SQLi. Hackers can use the data exposed by error messages to find more information about the database structure.

The union-based SQLi is carried out using the UNION SQL operator. It makes the database show a single HTTP response for different statements. The response can include information that can benefit the attackers. 

2. Inferential (Blind) SQLi

In this type of SQLi, the hackers transmit the data payloads to the server and check its response to get a better idea about the database structure and server. So, the blind SQL injections depend on the server responses and behavior. Hence, these are executed at a slow pace but can be as harmful as other attacks. 

3. Out-of-band SQLi

The out-of-band SQL injections can be launched only if certain functionalities are active on the web app’s database server. Here, the channel of attack and the channel of collecting data from the server are different. 

When attackers can’t use the same channel for interaction and gathering data, or if the server is unstable, they go with the out-of-band SQLi. They use it as an alternative to the in-band and blind SQL injection attacks. 

Test your knowledge with a quick quiz!

_______________ is time based SQL injection attack.

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SQLi Methodology

There are different types of SQL injection techniques that are used for a variety of scenarios. Hence, there is not a single method to launch SQL attacks. Following are some typical methods used by hackers to launch SQL injection attacks:

  • Retrieving and accessing the data that is hidden or not available to users. SQL queries are changed or manipulated to gather additional information.

  • Making changes to SQL queries for interfering with the logic of the application or system.

  • Launching UNION attacks to find access to data from multiple database tables.

  • Testing the database to extract sensitive data and information about the database structure and its version.

  • Another common method used here is blind SQL injection. 

Testing for SQLi Vulnerability

To test the SQL injection vulnerabilities, Burp Suite’s web vulnerability scanner is an efficient tool. 

It can also be done manually with the implementation of some tests against the entry points of the network, system, or app. These tests can be:

  • Entering SQL syntax that can check the base value of the entry point.

  • Entering single quote characters to find errors and relevant anomalies.

  • Entering Boolean conditions to find differences in the responses of the application.

  • Entering payloads that are created for triggering time delays when implemented within the SQL queries. It helps in checking out the differences in the time required for responses.

Advance SQLi Testing (SQLMAP)

SQLMAP is an advanced and automated tool for discovering SQL injections. It makes the process of SQLi testing easier and straightforward.

The tool runs a number of tests on the website and detects the flaws within a few minutes. SQLMAP also allows testing of particular parameters using the -p option. For maximum utilization of the tool, the use of the --headers option is great for passing the User-Agent header. The role of the --cookie option is to define the specific cookies with the queries.

The Power of SQL injection

The Power of SQL injection

Test your knowledge with a quick quiz!

All of the following are SQL vulnerabilities EXCEPT _____.

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