Welcome to the third course in the OWASP Top 10 series! 🛡️ In this course, we'll explore injection vulnerabilities, one of the most prevalent and dangerous security risks in modern web applications. Injection attacks occur when untrusted data is sent to an interpreter as part of a command or query, leading to the unintended execution of malicious code.

At its core, injection vulnerabilities arise when an application fails to properly validate, filter, or sanitize user-supplied input before using it in operations that interpret and process that input. The fundamental problem is a confusion of data and code. The application dynamically constructs a command—like a database query or a system command—by mixing trusted code with untrusted user data. When this is done insecurely (often through simple string concatenation), the interpreter cannot distinguish between the intended command and the malicious data provided by an attacker.

For example, consider a simple SQL query constructed with user input: query = "SELECT * FROM products WHERE category = '" + userInput + "';"

If a user provides a normal input like Gifts, the query works as expected. However, an attacker could provide a malicious input like ' OR '1'='1. The resulting query becomes: SELECT * FROM products WHERE category = '' OR '1'='1';

The OR '1'='1' is always true, causing the database to return all products, bypassing the intended logic. The attacker's input broke out of the data context and was executed as part of the SQL command. This is the essence of an injection attack: tricking an interpreter into executing unintended commands by supplying specially crafted data.

Injection vulnerabilities remain at the top of the OWASP Top 10 list because they are both common and potentially devastating. When exploited, these vulnerabilities can lead to a wide range of severe consequences:

• Data theft and loss: Attackers can use SQL injection to bypass authentication, read sensitive data from a database, or even modify and delete entire tables. This can lead to the exposure of user credentials, personal information, and financial records.
• System compromise: With OS Command Injection, an attacker can execute arbitrary commands on the host operating system. This could allow them to read sensitive files, install malware, or gain a persistent foothold on the server, potentially using it to pivot to other systems within the network.
• Application manipulation: Vulnerabilities like Server-Side Template Injection (SSTI) or Code Injection allow an attacker to execute code within the application's process. This gives them control over the application's logic, allowing them to access internal data, manipulate user sessions, or take over the application entirely.
• Service disruption: An attacker can submit a malicious query or command designed to consume excessive system resources (CPU, memory, or disk I/O). This can overload the server or database, leading to a Denial of Service (DoS) that makes the application unavailable to legitimate users.

These vulnerabilities don't just affect databases — they can target any system that interprets and processes user input, including operating system commands, file systems, and APIs.

Throughout this course, you'll learn how to identify and fix various types of injection vulnerabilities using our dummy pastebin application. You will:

• Prevent SQL injection in search features through parameterized queries.
• Implement safe command execution in file processing operations.
• Master prevention techniques including input validation and proper query construction.

By the end of this course, you'll understand how to properly validate and sanitize user input to prevent injection attacks in your applications.

In the next lesson, we'll explore SQL injection vulnerabilities in search functionality, a common attack vector where malicious actors can manipulate database queries. You'll learn how to identify vulnerable endpoints and implement proper input validation and parameterized queries to protect your application's data.

Let's begin our journey to securing applications against injection attacks! 🚀