Injection Attacks 101: Types, Risks, and Mitigation

What Are Injection Attacks?

Injection attacks occur when untrusted data is inserted into a program as part of a query or command, exploiting the system’s inability to validate and sanitize inputs properly. This type of attack often targets input fields, APIs, or communication between systems.

These attacks can target databases, servers, and client-side applications, causing data theft, system compromise, or even complete application failure.

What are the types of Injection Attacks?

Injection Type	Definition	Common Signs	Mitigation
SQL Injection (SQLi)	Attackers manipulate SQL queries to access or modify the database	SQL errors, unauthorized data access or manipulation	Use Prepared Statements, ORM frameworks, input validation, and least privilege database access
Command Injection	Attackers execute arbitrary OS commands through input fields	Unexpected command execution or system errors	Avoid using system commands directly, sanitize user inputs, and block special characters (e.g., &, `)
Cross-Site Scripting (XSS)	Attackers inject malicious scripts into web pages viewed by users	Unintended script execution or redirects, manipulated page content	Sanitize and escape inputs, implement Content Security Policy (CSP)
LDAP Injection	Attackers inject malicious LDAP queries to access or modify directory data	Unchecked input in LDAP queries, unauthorized data access	Use parameterized LDAP queries and validate inputs rigorously
XML Injection	Attackers manipulate XML data to affect XML parsing logic	Altered XML structure causing system errors or unexpected behavior	Validate XML input using a schema, use safe parsing functions
XPath Injection	Attackers manipulate XPath queries to gain access or modify data	Unchecked user input in XPath queries leading to unauthorized access	Sanitize inputs and use prepared queries or parameterized XPath expressions
NoSQL Injection	Attackers exploit NoSQL database queries to tamper with or view sensitive data	Unvalidated data in NoSQL queries causing unexpected behavior	Sanitize and validate inputs, use parameterized queries for NoSQL databases
OS Command Injection	Attackers inject OS commands through user inputs	Unsecured system commands causing unexpected system behavior	Avoid system calls with user input, sanitize inputs to block dangerous characters
Code Injection	Attackers inject code (e.g., PHP, JavaScript) into the application	Execution of injected code, unusual application behavior	Avoid evaluating user inputs as code, sanitize and validate inputs
Server-Side Template Injection	Attackers inject malicious templates into server-side rendering engines	Unchecked user input affecting template rendering or system logic	Validate and escape inputs before passing to template engines, disable dynamic template expressions
Prompt Injection	Attackers inject malicious input to manipulate AI models or prompts	AI systems providing unexpected or harmful outputs	Implement input validation, sanitize user inputs, and set clear input guidelines for AI models

1. SQL Injection (SQLi)

SQL Injection is one of the most widely known types of injection attack, where an attacker inserts malicious SQL statements into input fields, query strings, or form submissions to manipulate the database of an application.

When user input is not properly sanitized, attackers can craft input that alters the query structure. For example, using the input:

' OR '1' = '1',/code>

can change a query like:

SELECT * FROM users WHERE username = 'admin' AND password = 'password';

into:

SELECT * FROM users WHERE username = '' OR '1' = '1' AND password = '';

This query will always return true, allowing the attacker to bypass authentication.

Impact

• Unauthorized access to or modification of data
• Data theft (personal, financial, or business-critical information)
• Bypass of authentication mechanisms
• Potential for full control over the database

Want to dive deeper into how SQL injection works and how to prevent it? Check out our detailed guide on SQLi attacks and their mitigation strategies.

2. Command Injection

Command Injection occurs when an attacker injects malicious operating system commands into a vulnerable web application, which are then executed by the system. This attack is aimed at gaining unauthorized control over the operating system running the application.

Command injection often happens when an application takes user input and passes it directly to system commands without proper sanitization. For example, an attacker might input the following:

; rm -rf /

This would instruct the system to delete files, potentially causing irreparable damage.

Impact

• Unauthorized access to the underlying server
• File manipulation (deletion, modification)
• Complete compromise of the system
• Execution of arbitrary commands

3. Cross-Site Scripting (XSS)

A Cross-Site Scripting (XSS) attack is a type of web application vulnerability where an attacker injects malicious scripts into websites viewed by other users. These scripts are executed in the victim’s browser, allowing attackers to steal sensitive information, hijack sessions, or perform unauthorized actions.

Types of XSS Attacks

• Stored XSS: The malicious script is stored on the server and served to all users who visit the affected page. For instance, an attacker can input a script into a blog comment section, and the script will run whenever anyone views the comment.
• Reflected XSS: The injected script is immediately reflected by the web server and executed in the user’s browser. This typically happens when a user is tricked into clicking a malicious link that includes a malicious payload.
• DOM-Based XSS: A DOM-based XSS (Cross-Site Scripting) attack is a type of client-side vulnerability where the malicious script is executed by manipulating the Document Object Model (DOM) of a web page.

Impact

• Theft of session cookies and credentials
• Phishing attacks (redirecting users to fake sites)
• Defacement of websites
• Unauthorized actions on behalf of the user (e.g., posting messages or transferring funds)

Find out how XSS attack works and how to safeguard against it.

4. Code Injection

Code injection occurs when an attacker inserts malicious code into an application, causing it to execute in the same environment. Unlike command injection, code injection targets the application’s runtime environment rather than the operating system.

The attacker’s malicious code is executed within the context of the application. This type of injection may affect platforms like PHP, Python, or JavaScript. For example, the attacker might inject a script into a server-side script:

<?php eval($_GET['code']); ?>

By using eval(), the server executes whatever PHP code is injected through the code parameter.

Impact

• Remote code execution and full system compromise.
• Unauthorized access to sensitive data or system resources.
• Escalation of privileges.

5. LDAP Injection

LDAP (Lightweight Directory Access Protocol) Injection targets LDAP queries by injecting malicious input into the query, allowing attackers to manipulate the authentication process or access directory information.

LDAP queries are used to search for specific objects within a directory. If the input is not properly sanitized, an attacker can manipulate the query to return more data than intended, or even bypass authentication. For instance, an attacker might input:

(&(username=*)(password=))

This query may bypass password checks, allowing unauthorized access.

6. XML Injection

XML Injection attacks target applications that use XML data for configuration or communication, manipulating XML input to interfere with the processing of the XML document. An attacker manipulates XML data sent to an application, altering its structure or logic. A common scenario is exploiting poorly configured XML parsers or schema validation vulnerabilities.

Impact

• Bypass of authentication
• Unauthorized access to sensitive data
• Denial of Service (DoS) by exploiting XML parsers

Learn how XXE attack poses risks and how to prevent it.

7. XPath Injection

XPath Injection is a type of attack where an attacker manipulates an XML query by injecting malicious input into the XPath expression. XPath (XML Path Language) is a language used to query and extract data from XML documents, helping users pinpoint specific elements, attributes, or text within the XML structure.

When applications use user input to construct XPath queries without proper validation or sanitization, attackers can modify the query to bypass security controls, extract sensitive information, or perform unauthorized actions.

Web applications often use XPath queries to retrieve data from XML databases or files based on user input. For example, a login system may use an XPath query to check if a username and password exist in an XML file.

Example of an XPath query in code:

/users/user[name='%username%' and password='%password%']

If the user input (like username or password) is not properly sanitized, an attacker can inject malicious XPath expressions that modify the query’s logic.

Example of a malicious input:

• Username: admin’ or ‘1’=’1
• Password: any_password

This results in the following query:

/users/user[name='admin' or '1'='1' and password='any_password']

In this case, the condition ‘1’=’1′ will always be true, allowing the attacker to bypass authentication and gain unauthorized access.

8. NoSQL Injection

NoSQL Injection attacks target NoSQL databases like MongoDB, CouchDB, and others. These databases allow for flexible querying and lack the same constraints as SQL-based systems, which can be exploited by attackers.

NoSQL databases often accept more flexible input types (e.g., JSON or key-value pairs). An attacker can inject malicious queries using operators such as $ne (not equal) or $gt (greater than), bypassing application logic or authentication.

{ "username": { "$ne": null }, "password": { "$ne": null } }

Impact:

• Unauthorized access to sensitive data
• Bypass of authentication mechanisms
• Potential for data loss or modification

9. Email Header Injection

Email Header Injection occurs when attackers inject malicious content into email headers, which can be used to send unsolicited email (spam) or manipulate email functionality.

An attacker exploits an input field like “email” or “subject” to include new header lines (e.g., BCC:), allowing them to send emails to unintended recipients.

Impact:

• Sending unsolicited email to arbitrary recipients
• Bypassing email filtering systems
• Potential for phishing or spam attacks

10. Server side Template Injection (SSTI)

Server-Side Template Injection (SSTI) is a type of security vulnerability where an attacker can inject malicious templates into a server-side template engine. This can allow the attacker to manipulate the behavior of the server, execute arbitrary code, or disclose sensitive information. SSTI typically affects web applications that use template engines to dynamically render content (such as HTML or JSON) based on user input.

Example

A web application using a template engine like Jinja2 (Python) or Twig (PHP) might allow user input like this:

<p>{{ user_input }}</p>

If the application doesn’t sanitize the input properly, an attacker might inject code like this:

{{ config['secret'] }}

This would cause the server-side template engine to render the value of the secret configuration, exposing sensitive information.

11. Prompt Injection

Prompt Injection involves manipulating input sent to a model or application that uses AI-driven prompts (like ChatGPT or other large language models). By injecting specific prompts, attackers can manipulate the output, guiding the system to produce desired results.

Impact

• Misleading AI-generated outputs.
• Unauthorized access to sensitive information or bypassing AI safeguards.
• Exploitation of AI’s predictive capabilities for harmful purposes.

Recent Examples of Injection Vulnerabilities and Attacks

1. CVE-2023-34362: MOVEit Transfer SQL Injection Vulnerability

In May 2023, Progress disclosed a critical SQL injection vulnerability in MOVEit Transfer, identified as CVE-2023-34362. This flaw enabled unauthorized database access, making sensitive data vulnerable. It was exploited as a zero-day attack by attackers associated with the Clop ransomware group before the vulnerability was patched.

Impact: Databases were compromised, and sensitive information was stolen. The availability of proof-of-concept (PoC) code increased the likelihood of further exploitation by other malicious actors targeting unpatched systems.

2. CVE-2024-8190: OS Command Injection in Ivanti CSA

A critical OS command injection vulnerability, CVE-2024-8190, was discovered in Ivanti Cloud Services Appliance (CSA) versions 4.6 Patch 518 and earlier. Attackers, with elevated privileges, could execute malicious commands undetected, compromising the entire system.

3. CVE-2024-8517: Command Injection in SPIP’s BigUp Plugin

The CVE-2024-8517 vulnerability in SPIP’s BigUp plugin stemmed from improper input sanitization. Attackers exploited this flaw remotely without authentication. The vulnerability posed a high risk due to its ability to execute arbitrary OS commands via a malicious multipart file upload HTTP request.

The flaw led to full server compromises for websites running SPIP if exploited.

4. Hotjar OAuth+XSS Flaw

Hotjar, used by millions of websites for user behavior analytics, was found to have a critical vulnerability that combined OAuth misconfigurations with Cross-site Scripting (XSS).

Attackers could use legitimate-looking malicious links to gain OAuth credentials through an XSS attack. This would result in account takeovers and expose sensitive user data for websites using Hotjar, including global brands like Adobe and Microsoft.

Learn about the Hotjar OAuth+XSS Flaw

5. CVE-2023-37580: Reflected XSS in Zimbra Collaboration

On November 16, 2023, a reflected XSS vulnerability, CVE-2023-37580, was revealed in the Zimbra Collaboration Suite (ZCS). This flaw involved injecting malicious scripts via URL parameters, which were then executed in the victim’s browser. It enabled unauthorized access to sensitive data, session hijacking, and arbitrary code execution, posing a significant risk to Zimbra users.

How to Identify and Prevent Vulnerability to Injection Attacks

To determine if your application is vulnerable, follow these steps:

1. Conduct Security Audits and Code Reviews

Regularly audit your application code to identify areas where user inputs are processed (e.g., database queries, file uploads, or command execution).

Look for dynamic queries or commands that concatenate user inputs directly, as these are high-risk.

2. Perform Vulnerability Scanning

Use automated tools to scan for known injection vulnerabilities in your system.

Check for misconfigurations, unpatched components, and improper input handling.

Learn more in detailed our blog on vulnerability scanning.

3. Test with Malicious Inputs

Simulate injection attacks in a controlled environment to detect vulnerabilities. For example:

• SQL Injection: Input ‘ OR ‘1’=’1 into form fields and check for unintended results.
• Command Injection: Use inputs like ; ls or && whoami to see if commands are executed.
• XSS: Test by injecting <script>alert(‘XSS’)</script> into input fields to see if scripts execute.

4. Review Logs for Suspicious Activity

Monitor application logs for unusual activity, such as failed database queries or unauthorized commands. This can indicate injection attempts.

5. Validate Inputs on All Forms

Check if input fields enforce proper data types, length restrictions, and validation rules.

If user input is directly used in database queries, command execution, or scripts, it’s a red flag.

Strip or encode inputs to neutralize harmful characters like <, >, ‘, and ; that could enable injection attacks.

6. Use Vulnerability Databases

Cross-check your application components against CVEs (Common Vulnerabilities and Exposures) to see if known injection vulnerabilities exist in your dependencies.

7. Perform Penetration Testing

Engage professional penetration testers to identify injection vulnerabilities. They can simulate advanced attacks and identify weak points you may have missed.

Refer to our Penetration Testing Checklist for a comprehensive guide on preparing and executing effective penetration tests.

8. Use Security Headers

Inspect your application for missing headers like X-frame-options or X-Content-Type-Options. These can reduce the risk of certain types of injection attacks, such as XSS.

9. Use Parameterized Queries

Always use parameterized queries (also known as prepared statements) with placeholders for user inputs in database queries.

This eliminates the risk of SQL injection by separating query structure from user-provided data.

10. Implement Secure Coding Practices

Follow secure coding guidelines like those from OWASP and SANS to minimize vulnerabilities.

Train developers to recognize and avoid patterns that lead to injection flaws.

11. Deploy Web Application Firewalls (WAFs)

Use WAFs to monitor and block malicious traffic in real time.

Modern WAFs can identify and mitigate injection patterns automatically, providing an extra layer of protection.

12. Regularly Patch and Update Systems

Keep all software, frameworks, and libraries up to date. Vulnerabilities like SQL injection or OS command injection are often exploited in outdated versions of platforms.

Beyond just detecting vulnerabilities, addressing them promptly is crucial to maintaining security. AppTrana’s SwyftComply accelerates this process, ensuring zero open vulnerabilities within 72 hours.

13. Implement Content Security Policy (CSP)

A strong CSP helps protect against client-side attacks, like XSS, by restricting the execution of untrusted scripts.

Configure it to allow only trusted sources for executing scripts and loading resources.

14. Monitor for Anomalies

Use tools like Intrusion Detection Systems (IDS) and application logs to identify unusual patterns of activity that could signal an attack.

Set up alerts for suspicious activities, such as unauthorized database queries or unexpected file uploads.

15. Educate Your Team

Train your team on secure coding practices, common injection vulnerabilities, and mitigation techniques.

Raise awareness about the impact of poor input validation and insecure coding.

16. Utilize Secure Authentication and Authorization

Enforce strong authentication and limit access based on roles to minimize the risk of unauthorized interactions with critical systems.

Use the principle of least privilege to restrict access wherever possible.