DOM Vulnerabilities - DOM-based Cookie Manipulation скачать в хорошем качестве

DOM Vulnerabilities - DOM-based Cookie Manipulation

Support This Channel ====================== Please like and subscribe, it means a lot! Please buy me a coffee so I can continue to make content. https://buymeacoffee.com/zenshell Join our Discord   / discord   Exploring DOM-Based Cookie Manipulation for Cross-Site Scripting Attacks In this detailed walkthrough, we delve into the intricacies of DOM-based cookie manipulation and its potential to launch cross-site scripting (XSS) attacks. The core of this exploration lies in the ability to alter cookie values within a victim's browser, which subsequently affects the functionality of another page within the application. #### Understanding the Vulnerability The journey begins on a seemingly innocuous shop page within a lab environment designed to simulate a common web application. By navigating through the site, we observe that visiting a product page results in the creation of a "last viewed product" link on the homepage, a feature achieved through cookie storage. The cookie, named `last viewed product`, captures the product ID from the URL and retains this information for future reference. However, a deeper look into the JavaScript responsible for setting this cookie reveals a significant security oversight: the value of the cookie is dynamically assigned based on the current URL, which can be easily manipulated by altering the browser's address bar. This manipulation demonstrates the initial step towards exploiting the vulnerability. #### Exploiting the Vulnerability By appending additional parameters to the product page URL, we can modify the cookie's value. This manipulation becomes particularly concerning when returning to the homepage, where the altered cookie value is directly used within an anchor tag's `href` attribute. This misuse of cookie data for generating page content introduces the possibility of injecting arbitrary HTML or JavaScript into the page, laying the groundwork for a cross-site scripting attack. The crux of the attack unfolds as we craft a URL designed to not only append to the cookie's value but also to break out of the anchor tag and inject a script tag. Visiting this crafted URL doesn't visibly alter the page's functionality; however, inspecting the `last viewed product` cookie reveals the successful injection of our script. Upon returning to the homepage, the execution of the injected script is immediately evident, proving the concept of a reflected XSS attack facilitated by DOM-based cookie manipulation. This attack vector is potent, as it doesn't require any direct interaction with the server-side code; instead, it leverages the client-side DOM environment and the server's blind trust in cookie values. #### Conceptualizing the Attack The attack scenario involves enticing the victim to visit an attacker-controlled domain, where the vulnerable application is loaded within an iframe. The crafted URL, complete with the malicious script, is set as the iframe's source, leading to the alteration of the cookie's value upon loading. To ensure the execution of the XSS attack, the page is then redirected to the homepage within the same iframe, where the malicious script embedded in the cookie value is executed. The inclusion of an `onload` attribute in the iframe ensures that the redirection to the homepage occurs automatically, avoiding the need for the victim to visit the attacker-controlled domain multiple times. This automation significantly enhances the efficacy of the attack, emphasizing the importance of a single, well-crafted visit for successful exploitation. #### Concluding Thoughts This exploration into DOM-based cookie manipulation and its role in enabling cross-site scripting attacks underscores the critical importance of validating and sanitizing all user inputs, including those stored in cookies. The distinction between DOM-based and reflected XSS attacks in this context highlights the multifaceted nature of web vulnerabilities, urging developers and security professionals to adopt a comprehensive security posture that addresses both client-side and server-side risks. Thank you for joining this deep dive into a complex yet fascinating aspect of web security. Stay tuned for more insightful content in upcoming labs. 00:00 Intro 00:30 Exploring the Lab 01:27 Exploring Cookies 01:56 Dynamically Assigned Cookies Vulnerability 03:34 Breaking Out of the Anchor Tag 5:45 Crafting the Exploit 8:32 Solving the Lab and Summary