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April 24, 2023

What are Code Injection Attacks and 4 Ways to Prevent Them

What Is Code Injection?

Code injection is a type of cyber attack in which an attacker introduces malicious code into a vulnerable application or system, typically with the intention of executing unauthorized actions, stealing sensitive information, or gaining control over the system. This can be achieved by exploiting vulnerabilities in the target application, which might allow for the injection of code that would not normally be allowed.

Code injection is one of the most significant application security threats. In the OWASP Top 10 list of application security risks, last updated in 2021, “Injection”, which includes multiple types of code injection, is the third most significant threat.

Types of Code Injection Attacks

Cross-Site Scripting (XSS)

XSS is a type of code injection attack that targets web applications. In an XSS attack, an attacker may inject malicious JavaScript code into a vulnerable web page, typically by exploiting user input fields or other parts of the application that display user-generated content. When a user visits the infected page, the malicious script is executed in the user's browser.

This can lead to various harmful consequences, such as stealing sensitive information (e.g., cookies, session tokens), redirecting users to malicious websites, or performing actions on the user's behalf without their consent.

XSS attacks are typically classified into three categories:

  • Stored XSS: The malicious script is stored on the server (e.g., in a database or a file) and is executed whenever a user accesses the affected web page.
  • Reflected XSS: The malicious script is included in a URL or other user input and is executed when the user clicks on a crafted link or submits the input.
  • DOM-based XSS: The malicious script is injected into the Document Object Model (DOM) of the web page, often due to insecure client-side JavaScript code.

SQL Injection (SQLI)

SQLi is a code injection attack that targets database-driven applications. In an SQLi attack, the attacker inserts malicious SQL queries into user input fields or request parameters, which are then executed by the application's database.

This can lead to unauthorized access to data, data manipulation, or even complete control over the database. Common consequences of SQLi attacks include data leaks, data corruption, and unauthorized access to sensitive information.

LDAP Injection

LDAP (Lightweight Directory Access Protocol) Injection is an attack that targets applications that use LDAP for directory services. In an LDAP injection attack, the attacker injects malicious LDAP queries into user input fields or request parameters, exploiting vulnerabilities in the application's input validation or query construction. This can lead to unauthorized access to directory information, modification of directory data, or the bypassing of access controls.

Command Injection

Command Injection is a type of code injection attack that targets applications that use system commands or shell scripts. In a command injection attack, the attacker injects system commands into a vulnerable application, typically by exploiting insufficient input validation or insecure system configurations.

This can result in unauthorized access to the system, data manipulation, or even complete control over the system. Command injection attacks often involve the use of command separators or special characters to manipulate the command being executed, allowing the attacker to execute additional malicious commands.

How to Prevent Code Injection Attacks

Preventing code injection attacks involves implementing multiple security measures to protect applications and systems from unauthorized access and manipulation. Here are some key techniques to prevent these attacks:

1. Input Validation and Sanitization

Input validation ensures that only valid data is accepted by an application. By checking user-provided data against a set of rules or a specific format, developers can prevent the injection of malicious code. It is essential to perform input validation on both the client-side and server-side, as client-side validation can be bypassed by malicious users.

Sanitization is the process of cleaning or transforming user input to remove any potentially harmful content. This can include escaping special characters, removing or replacing disallowed characters, and applying filters to ensure data is safe to use within the application.

To effectively prevent code injection attacks, developers should:

  • Validate and sanitize all user input and external data sources (e.g., files, databases, APIs).
  • Use allowlists instead of blocklists to define acceptable input values.
  • Avoid relying solely on client-side validation, as it can be bypassed.

2. Parameterized Queries and Prepared Statements

Parameterized queries and prepared statements are techniques used to separate user input from SQL queries or other code constructs, reducing the risk of code injection attacks. In a parameterized query, placeholders are used instead of directly embedding user input into the query.

Prepared statements involve pre-compiling the SQL query with placeholders and then binding the user input to the placeholders before executing the query. Both techniques help prevent SQL injection attacks by ensuring that user input is treated as data and not as part of the query or command.

Developers should:

  • Use parameterized queries or prepared statements for all database interactions.
  • Avoid dynamically constructing SQL queries or other code constructs with user input.

3. Bug Bounty Programs

Bug bounty programs can play a significant role in preventing code injection attacks by incentivizing external security researchers to identify and report vulnerabilities in an organization's software or systems. Code injection attacks occur when an attacker injects malicious code into a vulnerable application, allowing them to execute unauthorized commands, compromise data, or gain control over the system.

Here's how bug bounty programs can help prevent code injection attacks:

  • Encourage proactive vulnerability discovery: By offering financial rewards or other incentives, bug bounty programs encourage security researchers to actively seek out vulnerabilities, including code injection flaws, in the organization's software. This proactive approach increases the chances of discovering and fixing vulnerabilities before attackers can exploit them.
  • Tap into the expertise of a diverse community: Bug bounty programs attract a wide range of security researchers, each with their own unique skillset and perspective. This diverse community can identify vulnerabilities that may have been overlooked by internal teams or automated testing tools.
  • Foster a security culture: Implementing a bug bounty program demonstrates an organization's commitment to security and encourages developers to adopt secure coding practices to avoid introducing vulnerabilities in the first place.

4. Least Privilege Principle

The principle of least privilege ensures that users, applications, and systems are granted the minimum level of access and permissions necessary to perform their tasks. By limiting access, the potential impact of a successful code injection attack can be reduced.

To implement the least privilege principle, developers should:

  • Limit the permissions of application accounts, services, and users.
  • Regularly review and update access controls to ensure they remain appropriate.
  • Use role-based access control (RBAC) to assign permissions based on user roles and responsibilities.


In conclusion, code injection attacks pose a significant threat to the security and integrity of applications and systems. By exploiting vulnerabilities in user input handling and other security weaknesses, attackers can inject malicious code or commands that allow unauthorized access to sensitive information, data manipulation, or control over the target system.

To defend against these attacks, developers must be proactive and implement a range of security measures, such as input validation and sanitization, parameterized queries and prepared statements, the principle of least privilege, and regular security testing.

Author Bio: Gilad David Maayan

Gilad David Maayan is a technology writer who has worked with over 150 technology companies including SAP, Imperva, Samsung (News - Alert) NEXT, NetApp and Check Point, producing technical and thought leadership content that elucidates technical solutions for developers and IT leadership. Today he heads Agile SEO, the leading marketing agency in the technology industry.

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