Quick take - Injection attacks, including various types such as Cross-Site Scripting (XSS) and SQL injection, present significant security risks to web applications by exploiting vulnerabilities to manipulate data, execute unauthorized commands, and potentially lead to data breaches and other malicious activities.

Fast Facts

Injection attacks threaten web applications through various vectors, including XSS, SQL injection, CRLF injection, SSTI, header injection, command injection, and directory traversal.
Cross-Site Scripting (XSS) has three main types: reflected, stored, and DOM XSS, each capable of stealing sensitive data or executing malicious code.
SQL Injection (SQLi) allows attackers to manipulate database queries, potentially extracting or altering data through crafted payloads.
CRLF injection can manipulate HTTP headers, leading to attacks like response splitting and request smuggling, while header injection can bypass authentication and cause SSRF.
To mitigate injection risks, security teams should rigorously test input fields and implement comprehensive protection strategies against various encoding techniques.

Injection Attacks: A Significant Threat to Web Applications

Injection attacks pose a significant threat to web applications, encompassing a variety of attack vectors. These include Cross-Site Scripting (XSS), SQL injection (SQLi), Carriage Return/Line Feed (CRLF) injection, Server-side Template Injection (SSTI), Header Injection, Command Injection, and Directory Traversal.

Types of Injection Attacks

Cross-Site Scripting (XSS)

Cross-Site Scripting (XSS) is a prominent type of injection attack. In XSS, an attacker injects arbitrary client-side code executed by a web browser within the context of a vulnerable application. XSS vulnerabilities can result in the theft of session tokens and sensitive data. There are three principal types of XSS attacks:

Reflected XSS: Involves malicious input reflected from the server and executed in the response. This often tricks users into clicking a harmful link.
Stored XSS: Occurs when the malicious payload is stored by the web application. It is then delivered to users who visit the affected page, impacting a wide audience.
DOM XSS: A vulnerability that occurs on the client side, altering the browser’s representation of the webpage.

SQL Injection (SQLi)

SQL Injection (SQLi) involves manipulating database query statements. This manipulation can extract, update, add, or delete information from a database. Attackers may use specific payloads to introduce delays in queries to identify vulnerabilities. They may also utilize the UNION clause to append additional queries, provided the queries maintain compatibility in the number of columns and data types.

Other Injection Techniques

Carriage Return/Line Feed (CRLF) Injection

Carriage Return/Line Feed (CRLF) injection allows attackers to manipulate HTTP headers. This manipulation can lead to various attacks such as user redirection to malicious domains, response splitting, and request smuggling, where a single request is interpreted as multiple requests.

Server-side Template Injection (SSTI)

Server-side Template Injection (SSTI) exploits vulnerabilities within web page templates, particularly when user input is concatenated into the templates. Header Injection can facilitate authentication and authorization bypasses, leading to server-side request forgery (SSRF) and web cache poisoning.

Command Injection and Directory Traversal

Command Injection enables attackers to execute operating system commands on a server through user-supplied input. Additionally, Directory Traversal and Local File Inclusion attacks allow unauthorized access to restricted directories, enabling attackers to read arbitrary files on a server.

Mitigation Strategies

To circumvent security measures, injection payloads can be obfuscated. Techniques include double URL encoding, employing encoded characters in HTML forms, utilizing SQL functions to bypass keyword filtering, and inserting non-disruptive characters into commands.

Injection vulnerabilities pose serious risks, including data breaches, data manipulation, account takeovers, remote code execution, and poisoning attacks. To mitigate these risks, security teams should rigorously probe input fields for vulnerabilities and implement comprehensive protection strategies that account for various characters and encodings, thereby enhancing defenses against injection attacks.

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