Cross Site Scripting (XSS) Testing – top vulnerability

Check your website for One of the most dangerous vulnerabilities placed in OWASP’s TOP 10.

Cross-site scripting (XSS) is a type of security vulnerability that occurs when an attacker injects malicious scripts into trusted websites viewed by other users. It takes advantage of the web application’s failure to properly validate and sanitize user input.

Here’s how the XSS attack typically unfolds:

1. The attacker injects malicious code: The attacker finds a vulnerability in a website that allows them to inject their own scripts or HTML code. This can be done through input fields, comment sections, or other areas where user input is accepted.
2. User visits the compromised website: When a user visits the compromised website, the malicious code is served along with the legitimate content. The user’s web browser does not distinguish between the injected code and the legitimate code.
3. Malicious code executes in the user’s browser: Once the user’s browser receives the malicious code, it executes it as part of the website’s content. This code can perform various actions, such as stealing sensitive information (like login credentials or personal data), manipulating the page’s content, redirecting the user to another site, or even launching further attacks.

There are three main types of XSS attacks:

1. Stored XSS: The injected malicious code is permanently stored on the target server and served to multiple users whenever they access the compromised page. This type of XSS is particularly dangerous as it can affect a large number of users.
2. Reflected XSS: The injected code is embedded in a URL or a form input, and the website includes it in the response without proper validation. When the user clicks on a manipulated link or submits a vulnerable form, the malicious code is reflected back and executed in their browser.
3. DOM-based XSS: This type of XSS occurs when the client-side JavaScript code manipulates the Document Object Model (DOM) of a webpage without proper sanitization. If the JavaScript code uses user-controlled data to modify the DOM, an attacker can inject malicious code by manipulating the input data.

To mitigate XSS vulnerabilities, web developers should implement proper input validation and output encoding. Input validation involves verifying and sanitizing user input to remove or neutralize potentially harmful code. Output encoding ensures that any user-generated content displayed on the website is properly encoded so that it is treated as data rather than executable code.

Users can also protect themselves by using web browsers with built-in XSS protection, keeping their browsers and plugins up to date, and being cautious when visiting unfamiliar or suspicious websites.

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