Listen to this Post
Payload: `’-alert?.(1)-‘`
You Should Know:
- Understanding DOM-based XSS: DOM-based XSS occurs when the attack payload is executed as a result of modifying the DOM environment in the victim’s browser. Unlike stored or reflected XSS, the payload is not sent to the server but is executed directly in the browser.
Payload Explanation: The payload `’-alert?.(1)-‘` is designed to bypass Cloudflare’s Web Application Firewall (WAF) by exploiting a DOM-based XSS vulnerability. The payload triggers an alert box with the value `1` when executed in the browser.
3. Testing for DOM-based XSS:
- Use browser developer tools (F12) to inspect the DOM and identify where user input is being injected.
- Inject the payload into input fields or URL parameters and observe if the alert box is triggered.
4. Mitigation Techniques:
- Input Validation: Ensure all user inputs are validated on both the client and server sides.
- Output Encoding: Encode data before rendering it in the browser to prevent malicious scripts from executing.
- Content Security Policy (CSP): Implement a strict CSP to restrict the sources from which scripts can be loaded.
5. Practice Commands:
- Linux Command to Test Web Application:
curl -X GET "http://example.com/search?q=<script>alert(1)</script>"
- Windows Command to Test Web Application:
Invoke-WebRequest -Uri "http://example.com/search?q=<script>alert(1)</script>"
- Using Burp Suite:
- Intercept the request using Burp Suite.
- Modify the request parameters to include the payload.
- Forward the request and observe the response.
6. Additional Resources:
What Undercode Say:
DOM-based XSS is a critical vulnerability that can be exploited to bypass security mechanisms like Cloudflare’s WAF. It is essential to understand how these vulnerabilities work and how to mitigate them. Always validate and sanitize user inputs, implement strict CSP policies, and regularly test your web applications for such vulnerabilities. The provided payload `’-alert?.(1)-‘` is a simple yet effective way to test for DOM-based XSS, but remember to use it responsibly and only in environments where you have permission to test.
Courses URLs:
References:
Reported By: Zlatanh Bypass – Hackers Feeds
Extra Hub: Undercode MoN
Basic Verification: Pass ✅
