What Is SQL Injection Attack

Introduction

SQL injection attack is a code injection method capable of wreaking havoc on databases.It empowers a hacker to gain unauthorized access to your valuable information, modify your database, or even erase it completely. That's the nightmare scenario SQL injection can bring to life.

Statistics paint a picture of the prevalence and severity of SQL injection attacks. According to the Open Web Application Security Project (OWASP), injection attacks ranked as the third most serious web application security risk in 2021. The organization discovered that in the apps they tested, there were over 274 thousand cases of attacks containing injections, which is an amazing number.

You need to understand SQL injection so as to safeguard your online assets. This guide focuses on providing knowledge about how these attacks are performed and what their possible consequences can be. Additionally, it will teach you some preventive measures against such harmful actions.

Overview

An SQL injection attack involves sneaking malicious SQL queries into the input data sent from a client to an application. This clever trick opens up many possibilities for wrongdoings.

The results of successful SQL injection exploits are devastating as they involve stealing private data and corrupting record sets held by databases; however, this is not everything because intruders who have succeeded may also use their privileges to tamper with database contents and run administrative commands.

By the end of this SQL injection tutorial, you should be well versed in them. You will be able to answer the question, “What is SQL Injection?” I will cover many forms of SQL injection attacks, their effects, how to stop them, and much more.

What Is An SQL Injection Attack?

Now let’s answer the question, “What is SQL Injection?”. SQL injection attacks are a serious threat stemming from a web security vulnerability that allows attackers to manipulate an application's database SQL queries. These attacks involve injecting malicious SQL commands into input fields, which can lead to a variety of undesirable outcomes.

Let me paint a picture of an SQL injection attack with an SQL injection attack example. Let’s say you're running an e-commerce website where users can search for products.

Now, suppose a malicious user decides to exploit a vulnerability in your search functionality by inputting malicious SQL commands instead of legitimate search terms. This could allow them to access sensitive information like customer payment details or even manipulate product prices. Now you know the answer to the question, “What is SQL Injection?”

Consequences Of A Successful SQL Injection Attack

It is very important to protect against SQL injection attacks and to be able to answer the question, “What is SQL Injection?”. Here are the consequences of a successful SQL injection attack;

• Exposes Sensitive Data: Attackers can retrieve and alter data, risking exposure to confidential information stored on the server.
• Compromises Users' Privacy: Private user data, such as credit card numbers, can be exposed depending on the information stored on the SQL server.
• Grants Attacker Administrative and General Access to Your System: Hackers can gain unauthorized access to the system using malicious code, if a database user has administrative privileges.
• Reputation Damage: High-profile data breaches caused by SQL injection attacks can lead to reputational damage and regulatory fines for organizations.
• Persistent Backdoor Access: In some cases, attackers can establish a persistent backdoor into an organization's systems, leading to long-term compromise that may go unnoticed for an extended period.
  

Types Of SQL Injection Attacks

Attackers have a few tricks up their sleeves when it comes to SQL injections (SQLi) attacks. SQL injection types are often divided into three categories: SQLi (Classic), Inferential SQLi (Blind), and Out-of-band SQL. These classifications are based on the methods attackers use to access backend data and the potential damage they can inflict. Let’s discuss them to better understand the term “What is SQL Injection?”

1. In-band SQL Injections Attacks

In-band SQL injection is a straightforward yet effective SQL Injection Attack, making it a go-to choice for many malicious actors. With this method, attackers use the same communication channel for both launching the attack and gathering results.

Let's illustrate with an example: Let’s say you're managing an online forum where users can search for posts. Now, suppose an attacker injects malicious SQL commands into the search bar, triggering error messages from the database. By analyzing these error messages, the attacker can glean insights into the database's structure and potentially access sensitive information.

Two common techniques within in-band SQL injection are:

(i) Error-based SQLi

Attackers manipulate the database to produce error messages, which they exploit to gather intel on the database's layout.

(ii) Union-based SQLi

This method leverages the UNION SQL operator to merge multiple select statements, obtaining a single HTTP response containing valuable data for the attacker. Consider a scenario where you're managing an online marketplace where users can search for products by category. Your application generates SQL queries to fetch product details based on user-selected categories. Here's the query:

txtCategory = getRequestString("Category");
txtSQL = "SELECT * FROM Products WHERE Category = '" + txtCategory + "'";

Now, imagine an attacker creates a URL like this:

http://www.example.com/products?Category=Electronics' UNION SELECT username, password FROM Users—

This URL triggers a SQL query like the following:

SELECT * FROM Products WHERE Category = 'Electronics' UNION SELECT username, password FROM Users--;

The attacker exploits the UNION SELECT statement to combine the request for electronic products with a query that retrieves usernames and passwords from the "Users" table. The result? The attacker gains access to sensitive user credentials and potentially compromises the security of your entire system.

2. Inferential (Blind) SQL Injections Attacks

Blind SQL injection takes a sneakier approach. Instead of directly receiving data from the database, attackers send payloads to the server and observe its response and behavior to deduce information about its structure. Since attackers don't receive feedback in-band, hence the term "blind," they rely on the server's response patterns.

Consider a scenario where an attacker is targeting a login page. By sending specific SQL queries and measuring the server's response time, the attacker can infer whether certain conditions are true or false. This method may be divided into several categories:

• Boolean injection: Attackers gauge the truthfulness of results based on whether the HTTP response was altered.
• Time-based injection: Attackers induce delays in server responses and analyze the timing to determine the validity of their queries.

3. Out-of-band SQL Injections Attacks

Less common but equally potent, out-of-band SQL injection comes into play when certain server features are enabled. Unlike in-band methods, where attackers use the same channel for attack and data retrieval, this SQL injection attack example necessitates alternative channels due to server limitations or security measures.

This type of SQL injection attack occurs in a scenario where an attacker exploits a web application's poorly configured database server. Unable to retrieve data through the standard communication channel, the attacker orchestrates DNS or HTTP requests to transfer information covertly.

Different Ways SQL Injection Attacks Are Performed

When an attacker sets their sights on executing a SQL injection attack, they're essentially aiming to manipulate a standard SQL query to exploit vulnerabilities in a database's input validation. Let's explore some of the methods attackers employ to carry out these nefarious attacks.

1. SQL Injection Based on 1=1 is Consistently True

Let’s say you're managing a blog platform where users can search for articles by entering article IDs. Your code for retrieving articles might look something like this:

txtArticleId = getRequestString("ArticleId");
txtSQL = "SELECT * FROM Articles WHERE ArticleId = " + txtArticleId;

Now, suppose an attacker submits a malicious input like:

ArticleId: 123 OR 1=1;

This transforms the SQL statement into this query "SELECT * FROM Articles WHERE ArticleId = 123 OR 1=1;" retrieves all articles from the "Articles" table. This is so that all entries are returned and the provided ArticleId filter is bypassed because the criterion "1=1" always evaluates to TRUE. The query returns all articles from the "Articles" table, regardless of the supplied ID, because "1=1" always evaluates to TRUE. If your articles contain sensitive information like user comments or personal details, the attacker gains unrestricted access to this data.

2. SQL Injection Based on ""="" is True

Imagine you're managing an online banking platform where users log in with their account numbers and PINs. This is how your login code may appear:

accNum = getRequestString("account_number");
pin = getRequestString("pin");
sql = 'SELECT * FROM Accounts WHERE AccountNumber ="' + accNum + '" AND PIN ="' + pin + '"'

Now, imagine an attacker attempts to exploit this login form by entering the following credentials:

Account Number: " OR ""="
PIN: " OR ""="

This manipulation results in the following SQL query being executed:

SELECT * FROM Accounts WHERE AccountNumber ="" or ""="" AND PIN ="" or ""=""

Since the condition ""="" always evaluates to TRUE, the query returns all rows from the "Accounts" table, effectively granting the attacker unrestricted access to user accounts.

Real-life Examples Of SQL Injection Attacks

These real-life examples underscore the severity and widespread impact of SQL injection attacks. No sector is immune to the devastating consequences of these security vulnerabilities. It affects financial institutions, entertainment industries, and even tech giants. Here are some real-life examples:

1. Heartland Payment Systems (2008)

Heartland Payment Systems, a prominent payment processing corporation, suffered one of history's greatest data breaches as a result of an SQL Injection attack.About 130 million credit and debit card numbers were compromised.

2. Sony Pictures (2011) A Virtual Nightmare In 2011

Entertainment giant Sony Pictures faced a massive cyber assault, compromising around 77 million PlayStation Network accounts and resulting in a financial loss of approximately $170 million.

3. Yahoo! (2012)

A Massive Data Breach In July 2012, Yahoo! experienced a colossal data breach, leaking around half a million passwords and email addresses associated with Yahoo! Voices.

4. Cisco (2018)

A SQL injection vulnerability in the Cisco Prime License Manager allowed attackers to gain shell access to vulnerable systems.

5. Fortnite (2019)

An SQL injection vulnerability in the popular online game Fortnite could have allowed attackers to access user accounts.

6. Tesla (2014)

Using SQL injection, security researchers were able to penetrate Tesla's website, get administrator rights, and steal user data.

7. HBGary Breach

HBGary, an IT security company, fell victim to hackers associated with the Anonymous activist group, who used SQL Injection to take down the company's website.

Best Practices To Protect And Prevent Your Database And Websites From SQL Injection

Here are nine tips for SQL injection prevention. Follow these tips to protect against SQL injection and understand more about “What is SQL Injection.” These tips will help protect your Websites and databases from SQL injection attacks.

1. Keep Software Up-to-Date

Regularly install the latest software and security patches from vendors to ensure your system is equipped with the latest defenses against SQL injection attacks.

2. Limit Privileges

Give accounts connecting to the SQL database only the necessary privileges to perform their tasks. It reduces the potential impact of a compromised account.

3. Avoid Shared Accounts

Do not share database accounts across different websites and applications to prevent attackers from gaining widespread access in case of a breach.

4. Implement Input Validation

Use validation for all user-supplied input, including drop-down menus, to ensure that only valid and expected data is processed by your application.

5. Configure Error Reporting

Configure error reporting to handle errors internally and don’t send detailed error messages to the client web browser, which could expose sensitive information to attackers.

6. Use Prepared Statements

Utilize prepared statements with parameterized queries to define all SQL code and pass in each parameter securely, preventing attackers from altering query intent.

7. Use Stored Procedures

Build SQL statements with framework that are stored in the database, enhancing security by minimizing direct interaction with SQL queries.

8. Implement Allowlist Input Validation

Implement allowlist input validation to restrict user input to predefined acceptable values. This will help reduce the risk of unvalidated input being added to queries.

9. Employ Input Sanitization and Parameterized Queries

Use input sanitization techniques to clean and validate user input, removing or escaping potentially malicious characters before processing it in SQL queries.

Additionally, parameterized queries can be made to securely pass user input as parameters, preventing SQL injection attacks by separating user data from the SQL code execution. Input sanitization and parameterized queries are crucial defense mechanisms against SQL injection attacks, helping to ensure the integrity and security of your database and web applications.

Conclusion

Cyber threats continue to loom at large. Therefore, it is important to understand and defend against SQL injection attacks. You may do this by understanding how SQL injection works, answering the question "What is SQL Injection?" and implementing robust security measures. We have explained all of this in this SQL injection tutorial.

Real-world scenarios should act as a vivid reminder of how much harm can be done to any organization in any industry through SQL injection attacks.

Remember to follow recommended practices, including updating software, restricting rights, and performing thorough input validation. This will help you enhance your SQL injection defense.

FAQs

1. What is a real-life example of SQL injection?

A real-life example of SQL injection is the Heartland Payment Systems breach in 2008, where approximately 130 million card numbers, both debit and credit, were compromised.

2. Why do hackers use SQL injection?

Hackers are using SQL injection to find the weaknesses of websites and applications, which help them enter databases illegally and control or steal private data.

3. Are SQL injection attacks illegal?

Yes, SQL injection attacks are illegal. These actions involve breaking into computer systems and unauthorized access to information, therefore breaching cybersecurity and data protection laws.

4. What are the five types of SQL injection?

Five types of SQL injection include In-band SQLi (Classic), Inferential SQLi (Blind), Out-of-band SQLi, Boolean-based SQLi, and Time-based SQLi.

5. What is the most common SQL injection?

The most common type of SQL injection is In-band SQLi (Classic), where the attacker utilizes the same communication channel for the attack and to collect results.

6. Is SQL injection a virus?

Not at all; SQL injection is not a virus. It's a type of cyber-attack where malicious SQL queries are injected into input fields of web applications to manipulate databases.

7. How powerful is SQL injection?

SQL injection can be incredibly powerful, allowing attackers to gain unauthorized access to databases, extract secret records, modify or delete data, and even execute administrative commands on the server.

8. Is SQL injection a tool?

SQL injection itself is not a tool, but there are tools available that automate the process of identifying and exploiting SQL injection vulnerabilities in web applications.

9. What is the risk of SQL injection?

Risks that come with SQL injections include but are not limited to unauthorized access to sensitive data, alteration or deletion of records, infringement upon user confidentiality, financial loss, and damage to reputation.

10. Is SQL injection still a threat?

The answer is yes, it does. Even though many security measures have been implemented against this type of attack, various sites and apps can still be easily exploited through SQL injection.