Web Pentesting Stored XSS

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Web Pentesting Stored XSS

Web pentesting, short for web penetration testing, is the process of testing the security of a web application to identify potential vulnerabilities that could be exploited by attackers. One common vulnerability that web applications may have is called Stored Cross-Site Scripting (XSS).

Stored XSS is a type of XSS attack in which an attacker injects malicious code into a web application that is then stored on the server and served to users who access the affected page. The code is executed in the context of the user's browser, which can allow the attacker to steal sensitive information, such as login credentials, or perform actions on the user's behalf, such as making unauthorized purchases.

To test for Stored XSS, a web pentester can follow these steps:

Step 1. Identify input fields that allow user-generated content, such as comment boxes, search bars, or contact forms.

Step 2. Craft a payload that contains JavaScript code that can execute in the context of the victim's browser. The payload should be able to steal cookies, redirect the user to a malicious website, or perform other malicious actions.

Step 3. Submit the payload in the input field and check if it is stored on the server and served to other users who access the page.

Step 4. If the payload is executed when the page is loaded, then the web application is vulnerable to Stored XSS and the pentester should report it to the application's owner or developer.

To prevent Stored XSS attacks, web developers can implement input validation and sanitization techniques to remove or encode any special characters that can be used to inject malicious code. They can also implement Content Security Policy (CSP) headers to restrict the types of resources that can be loaded by the page and prevent untrusted code from executing.