How to Validate XSS Payloads in Redirect Pages Using Caido

By /

Listen to this Post

Featured Image

Introduction

Cross-Site Scripting (XSS) remains a critical web vulnerability, but validating payloads in redirect responses can be challenging. When a payload is reflected in a redirect page, the browser may not execute it due to the HTTP 3xx status code. This article explores how to use Caido’s Match and Replace (M&R) rule to bypass this limitation and confirm XSS exploitation.

Learning Objectives

  • Understand why XSS payloads fail in redirect responses.
  • Learn how to configure Caido to modify HTTP status codes for validation.
  • Apply this technique in real-world bug bounty hunting scenarios.

1. Bypassing Redirects with Caido Match and Replace

Command/Configuration:

 Caido M&R Rule to Replace 302 with 200 
match: 
response: 
status_code: 302 
replace: 
response: 
status_code: 200

Step-by-Step Guide:

  1. Open Caido and navigate to the Match and Replace rules section.
  2. Add a new rule targeting responses with a `302` (or 301, 307) status code.
  3. Replace the status code with `200 OK` to force the browser to render the response.
  4. Resend the XSS payload—the alert should now execute.

2. Validating XSS Payloads with Manual Testing

Command (Browser Console):

fetch('/redirect-endpoint', { 
redirect: 'manual' 
}).then(res => res.text()).then(html => document.write(html));

Steps:

  1. Use the browser’s developer console to send a request with redirect: 'manual'.
  2. Extract the response body and inject it into the DOM.
  3. Check for payload execution without following the redirect.

3. Automating with Python Requests

Code Snippet:

import requests 
response = requests.get('https://vulnerable.site/redirect', allow_redirects=False) 
if '<script>alert(1)' in response.text: 
print("XSS Confirmed!")

Steps:

1. Disable redirects using `allow_redirects=False`.

2. Analyze the response body for reflected payloads.

4. Burp Suite Interception

Tool Configuration:

  1. In Burp Suite, go to Proxy > Options and enable Intercept Server Responses.
  2. Drop the redirect response and manually inspect the body for XSS.

5. Browser Extensions for Debugging

Tool: “Redirector” (Chrome/Firefox Extension)

Steps:

  1. Configure the extension to block redirects from the target domain.
  2. Reload the page to view the raw response.

What Undercode Say

  • Key Takeaway 1: Redirect-based XSS is often overlooked but can be critical in bug bounty programs.
  • Key Takeaway 2: Tools like Caido and Burp Suite simplify validation by manipulating HTTP flow.

Analysis:

While traditional XSS testing focuses on direct reflection, advanced techniques like status code manipulation reveal hidden vulnerabilities. This approach is particularly useful for single-page applications (SPAs) and OAuth flows, where redirects are common. As browsers tighten default security policies, ethical hackers must adapt with tool-assisted testing.

Prediction

Future web frameworks may enforce stricter validation on redirect responses, but attackers will pivot to DOM-based XSS or server-side prototype pollution to achieve similar results. Proactive testing will remain essential.

Further Resources:

IT/Security Reporter URL:

Reported By: Deepak Saini – Hackers Feeds
Extra Hub: Undercode MoN
Basic Verification: Pass ✅

🔐JOIN OUR CYBER WORLD [ CVE News • HackMonitor • UndercodeNews ]

💬 Whatsapp | 💬 Telegram

📢 Follow UndercodeTesting & Stay Tuned:

𝕏 formerly Twitter 🐦 | @ Threads | 🔗 Linkedin

Related Posts: