Are you aware of the Second-Order SQL Injection? If not, we will travel over Second Order SQL Injection's definition, working, possible outcomes, and a thorough example to help you demonstrate the concept in this complete guide.

Pinpointing SQL Injection

It is a common online application security vulnerability known as SQL injection where an attacker can modify SQL queries created by an application. However, unintentional implications like unwanted access, data leakage, or data change could result from this manipulation.

Second Order SQL Injection: What Is It?

The second-order SQL Injection appears when an application receives user input. It stores that data—usually in a database—and then uses that saved data in a SQL query, known as SQL Injection. 

As compared to conventional SQL injection, which initiates the injected code right away, in Second Order SQL Injection, the execution is postponed until the stored data is retrieved and used in a subsequent query.

How does Second Order SQL Injection work?

This process breakdown into the following phases:

Stage of Injection

The attacker injects the perilous SQL code into the app, but it is not immediately enacted. Rather, it is kept in the database, oftentimes seeming harmless and evading security measures.

Stage of Execution

Subsequently, the program recovers the malicious code that was stored and runs it as a piece of a valid SQL query for a different task.

How does it contrast with First-Order SQL Injection?

Slow implementation

Moreover, Second-order SQL Injections execute harmful code unexpectedly when there is a specific event or condition, rather than happening instantly.

Difficulty in noticing

Additionally, detecting them is more difficult because the data may appear harmless when stored initially.

Second-order SQL Injection example

Moreover, to enhance awareness of second-order SQL injection, let us explore an example.

Initially, suppose a simple web application where users may post product reviews, which are then saved in a database.

• User A submits the first review, who writes, "This product is great!"
• Because the program fails to properly validate the input before storing this review in the database, the following SQL query is run:

SQL

INSERT INTO product_reviews (user_id, review_content) VALUES (1, 'This product is great!');

• An attacker named User B adds a review with malicious content: "'; DELETE FROM product_reviews WHERE 1=1; --"

• The program runs the following SQL query to store this malicious review in the database:

INSERT INTO product_reviews (user_id, review_content) VALUES (2, ''; DELETE FROM product_reviews WHERE 1=1; --');

• The application retrieves the reviews from the database and shows them without the necessary validation later on when an administrator checks the list of reviews:

SQL

SELECT * FROM product_reviews;

• The application generates the following output:

SQL

Review 1: This product is great!
Review 2: ''; DELETE FROM product_reviews WHERE 1=1; --

• The fraudulent input from the attacker is processed, erasing every product review:

SQL

DELETE FROM product_reviews WHERE 1=1;

However, by posting a seemingly benign review, the attacker was able to introduce malicious SQL code into the application. The application's failure to retrieve and present saved reviews without sufficient input validation resulted in the unintentional deletion of all product reviews.

Upshots (Significances)

Exfiltration of Data

Additionally, attackers can extract sensitive data from the database, such as user credentials, personal information, or financial records.

False Data

Cyber-punks can alter or remove data, which could result in lost data or interrupted services.

Bypassing Authentication

In addition, by using second-order SQL injection, unauthorized portions of an application can be accessed without authorization.

Issues with Data Integrity

However, inaccurate data can cause problems with the database integrity of the program, making it untrustworthy.

Preventive Measures

In addition, to prevent second-order SQL injection vulnerabilities, secure coding techniques, and input validation are necessary.

Input Confirmation

Before using any inputs in SQL queries, thoroughly verify them all, including those that are received from the database.

Prepared Statements

To keep SQL logic and data separate, use prepared statements in meeting with parameterized queries.

Exiting the user input

Apply appropriate methods for escaping special characters in user inputs.

Permissions for Databases

By restricting database permissions, you can implement the least liberty concept.

Use  Object-Relational Mapping (ORM) Tools

SQL Injection attack risk can be decreased by using ORM tools to conceptualize database interactions and assist in evading the creation of direct SQL queries.

In brief

The danger of second-order SQL injection is that it is subtle and can pass through many of the defenses put in place against conventional SQL injection. It takes advantage of people's confidence in the information stored by the database system by assuming that the data in the database is already secure. Lastly, Second-order SQL Injection must be avoided by any web application from a cybersecurity standpoint.