CVE-2023-4203 – This stored cross-site scripting (XSS) vulnerab... (How to Fix)

Q: What is the severity of CVE-2023-4203?

CVE-2023-4203 has a CVSS score of 9.0 (CRITICAL). This stored cross-site scripting (XSS) vulnerability in Advantech EKI-1524, EKI-1522, and EKI-1521 devices allows authenticated attackers to inject malicious scripts into the ping tool of the web interface. When other users access the affected page, the scripts execute in their browsers, potentially stealing credentials or performing unauthorized actions. Only authenticated users can exploit this vulnerability.

📋 TL;DR

This stored cross-site scripting (XSS) vulnerability in Advantech EKI-1524, EKI-1522, and EKI-1521 devices allows authenticated attackers to inject malicious scripts into the ping tool of the web interface. When other users access the affected page, the scripts execute in their browsers, potentially stealing credentials or performing unauthorized actions. Only authenticated users can exploit this vulnerability.

💻 Affected Systems

Products:

Advantech EKI-1524
Advantech EKI-1522
Advantech EKI-1521

Versions: Through version 1.21

Operating Systems: Embedded firmware

Default Config Vulnerable: ⚠️ Yes

Notes: All devices running affected firmware versions with web interface enabled are vulnerable. Authentication is required to exploit.

📦 What is this software?

⚠️ Risk & Real-World Impact

🔴

Worst Case

An authenticated malicious user could steal administrator credentials, hijack sessions, redirect users to malicious sites, or perform administrative actions on behalf of other users, potentially leading to full device compromise.

🟠

Likely Case

Authenticated attackers with lower privileges could escalate privileges by stealing administrator cookies/sessions, leading to unauthorized configuration changes or device takeover.

🟢

If Mitigated

With proper input validation and output encoding, the malicious scripts would be rendered harmless as text rather than executable code.

🌐 Internet-Facing: HIGH

🏢 Internal Only: MEDIUM

🎯 Exploit Status

Public PoC: ⚠️ Yes

Weaponized: LIKELY

Unauthenticated Exploit: ✅ No

Complexity: LOW

Exploit details and proof-of-concept are publicly available. Attack requires authenticated access to the web interface.

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: Unknown

Vendor Advisory: Not available

Restart Required: No

Instructions:

Check Advantech website for firmware updates. If available, download latest firmware and follow vendor upgrade procedures.

🔧 Temporary Workarounds

Restrict Web Interface Access

all

Limit access to the device web interface to trusted networks only using firewall rules.

Disable Ping Tool

all

If ping functionality is not required, disable or restrict access to the ping tool in the web interface.

🧯 If You Can't Patch

Implement strict network segmentation to isolate affected devices from critical networks
Enforce strong authentication policies and monitor for suspicious authenticated user activity

🔍 How to Verify

Check if Vulnerable:

Check device firmware version via web interface. If version is 1.21 or earlier, device is vulnerable.

Check Version:

Login to web interface and check System Information or About page for firmware version

Verify Fix Applied:

Verify firmware version is later than 1.21. Test ping tool with XSS payloads to confirm they are properly sanitized.

📡 Detection & Monitoring

Log Indicators:

Unusual ping tool usage patterns
Multiple failed authentication attempts followed by successful login
Web interface access from unexpected IP addresses

Network Indicators:

HTTP requests containing script tags or JavaScript in ping tool parameters
Unusual outbound connections from device after web interface access

SIEM Query:

source="advantech_web_logs" AND (uri="/ping" OR uri="/cgi-bin/ping") AND (query CONTAINS "<script>" OR query CONTAINS "javascript:")

📊 Metadata

CVE ID: CVE-2023-4203

CVSS v3 Score: 9.0 (CRITICAL)

CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:H

CWE: CWE-79

Published: August 8, 2023

Last Updated: February 13, 2025

🔗 References

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