Discovered a Malicious SVG: Understanding XSS Threats in SVG Files

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While scanning files, a malicious SVG was discovered containing an embedded XSS (Cross-Site Scripting) vector. This highlights a critical security gap—many hosting providers only address threats on primary domains, ignoring subdomains, which can be equally dangerous.

You Should Know: How Malicious SVG Files Work

SVG (Scalable Vector Graphics) files are XML-based and can include JavaScript, making them a potential vector for XSS attacks. Attackers exploit this by embedding malicious scripts that execute when the SVG is rendered in a browser.

Example of a Malicious SVG Code


<svg xmlns="http://www.w3.org/2000/svg" onload="alert('XSS')">
<script>alert("Malicious Script Executed!")</script>
</svg>

If this SVG is opened in a vulnerable browser, the script executes automatically.

How to Detect Malicious SVG Files

1. Manual Inspection

  • Open the SVG in a text editor and check for `