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Types of XSS Vulnerabilities: Understanding the Different Forms of Cross-Site Scripting

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Cross-site scripting (XSS) is a type of security vulnerability that allows attackers to inject malicious code into web pages viewed by other users. This can lead to a range of attacks, from stealing sensitive information to taking control of user accounts. There are several types of XSS vulnerabilities, each with its own unique characteristics and potential impact. In this article, we’ll explore the different forms of XSS and how they can be prevented.

Reflected XSS

Reflected XSS occurs when an attacker injects malicious code into a URL or form input field that is then reflected back to the user in the response page. For example, if a search box on a website doesn’t properly sanitize user input, an attacker could enter JavaScript code that would execute when another user searches for something similar.

This type of attack is often used in phishing scams or to steal sensitive information such as login credentials or credit card numbers. To prevent reflected XSS attacks, it’s important for developers to properly sanitize all user input and encode any output sent back to users.

Stored XSS

Stored XSS occurs when an attacker injects malicious code into a web application’s database or other storage mechanism. This code is then served up whenever another user accesses the affected page or data.

One common example is through comments on blog posts or forums where attackers can insert JavaScript code that executes whenever someone views those comments. Stored XSS attacks can be particularly dangerous because they don’t require any interaction from users – simply viewing the affected content can trigger the attack.

To prevent stored XSS attacks, developers should ensure that all data entered by users is sanitized before being stored in databases or other storage mechanisms. Additionally, regular security audits should be conducted to identify any vulnerabilities in existing systems.

DOM-Based XSS

DOM-based XSS occurs when an attacker injects malicious code into a web page’s Document Object Model (DOM) rather than the server-side code. This type of attack is often more difficult to detect and prevent because it doesn’t involve any server-side processing.

One common example is through URL parameters that are used to modify the behavior of JavaScript functions on a page. If these parameters aren’t properly sanitized, an attacker could inject malicious code that executes whenever someone visits that URL.

To prevent DOM-based XSS attacks, developers should ensure that all client-side scripts are properly validated and sanitized before being executed. Additionally, regular security audits should be conducted to identify any vulnerabilities in existing systems.

Conclusion

XSS vulnerabilities can have serious consequences for both users and businesses alike. By understanding the different types of XSS attacks and how they can be prevented, developers can help protect their applications from these types of threats.

To summarize, reflected XSS occurs when an attacker injects malicious code into a URL or form input field that is then reflected back to the user in the response page; stored XSS occurs when an attacker injects malicious code into a web application’s database or other storage mechanism; and DOM-based XSS occurs when an attacker injects malicious code into a web page’s Document Object Model (DOM). To prevent these types of attacks, developers should ensure that all user input is properly sanitized before being processed or stored, client-side scripts are validated and sanitized before execution, and regular security audits are conducted to identify any vulnerabilities in existing systems.

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