Stored xss

Definition

Stored XSS, also known as persistent XSS, is a type of cross-site scripting vulnerability where an attacker injects malicious scripts into a web application, and these scripts are then stored on the server. This means that whenever a user accesses a compromised page, the malicious script runs in their browser without their consent, potentially leading to data theft or account hijacking. This vulnerability is particularly dangerous because it can affect multiple users who view the affected content.

5 Must Know Facts For Your Next Test

1. Stored XSS vulnerabilities can be found in any application that allows users to submit data that gets stored, like comments, forum posts, or user profiles.
2. Attackers exploit stored XSS by crafting malicious scripts that are embedded in the data submitted by a user, which can then be executed by unsuspecting visitors to the affected web page.
3. The impact of stored XSS can range from stealing session cookies and personal information to redirecting users to phishing sites.
4. Preventing stored XSS requires proper input validation and output encoding to ensure any user-submitted data is treated as plain text rather than executable code.
5. Stored XSS is often listed among the top web application security risks by organizations like OWASP due to its potential for widespread impact on users.

Review Questions

• What makes stored XSS particularly dangerous compared to other types of cross-site scripting?
  • Stored XSS is particularly dangerous because the malicious scripts are saved on the server and can affect multiple users who access the compromised content. Unlike reflected or DOM-based XSS, where attacks typically target individual users through specific URLs or client-side manipulations, stored XSS can lead to widespread exploitation since any user visiting the affected page executes the injected script. This makes it a high-risk vulnerability in web applications.
• Discuss how proper input validation can mitigate the risks associated with stored XSS vulnerabilities.
  • Proper input validation is crucial in mitigating stored XSS risks because it ensures that any data submitted by users does not contain potentially harmful scripts. By implementing strict rules for what types of characters or code snippets can be accepted in user inputs, developers can prevent attackers from injecting malicious scripts into the system. Additionally, sanitizing and escaping outputs will help in rendering any user-generated content safely in the browser, further reducing the risk of execution of harmful scripts.
• Evaluate the implications of stored XSS for web application security practices and user trust.
  • Stored XSS significantly impacts web application security practices as it emphasizes the need for robust security measures that protect user data and maintain trust. When users fall victim to stored XSS attacks, it can lead to unauthorized access to their accounts, data breaches, and loss of personal information. This not only undermines user trust but also damages the reputation of web applications. As a result, developers must prioritize secure coding practices, regular security audits, and user education about recognizing potential threats to safeguard both the application and its users.

Related terms

Reflected XSS: A type of cross-site scripting where the malicious script is reflected off a web server and executed immediately, typically through a URL.

DOM-based XSS: A form of cross-site scripting that occurs when the client-side script modifies the DOM of the page, leading to execution of harmful scripts.

Input Validation: The practice of validating user inputs to ensure they are safe and do not contain potentially harmful content.