CVE-2023-28962 - Improper Authentication Vulnerability in Juniper Networks Junos OS: A Deep Dive into the Exploit

The Common Vulnerabilities and Exposures (CVE) system recently added a new vulnerability, CVE-2023-28962, to its database. This vulnerability is associated with an Improper Authentication issue in the upload-file.php script, a component present in Juniper Networks' Junos OS. This vulnerability allows an unauthenticated, network-based attacker to upload arbitrary files to temporary folders on the device.

Code Snippet

In the affected Junos OS versions, the upload-file.php script does not properly authenticate users before allowing file uploads. Here is a sample code snippet that demonstrates the issue:

<?php
/* upload-file.php - vulnerable script in Junos OS */
if ($_SERVER['REQUEST_METHOD'] == 'POST' && isset($_FILES['uploaded_file'])) {
    // Missing authentication check for the user
    $tmp_name = $_FILES['uploaded_file']['tmp_name'];
    $dest_path = "/tmp/uploads/" . basename($_FILES['uploaded_file']['name']);
    move_uploaded_file($tmp_name, $dest_path);
}
?>

As seen from the code snippet, the authentication check is missing, which allows any user to upload a file without authentication.

Exploit Details

An attacker can exploit this vulnerability by uploading malicious files to the device's temporary folder. This may lead to various undesirable outcomes, such as:

1. Remote code execution - the attacker can upload and execute malicious scripts, granting unauthorized access to the device and potentially the network.
2. Denial of service - by uploading large files, the attacker can consume storage space on the device, eventually causing it to crash or cease functioning.
3. Data exfiltration - the attacker can upload files to gather sensitive information or directly exfiltrate data from the device.

The vulnerability was first reported by Juniper Networks in the following security advisory

- JSA11192 - 2022-03 Security Bulletin: Junos OS: J-Web: Unauthenticated file uploads

Moreover, NIST National Vulnerability Database (NVD) has also reported the vulnerability with detailed information:
- CVE-2023-28962 Detail

Mitigation

Users of affected Junos OS versions are advised to update their systems to the latest fixed releases as mentioned in the Juniper security advisory. Additionally, users can implement the following security practices:

Conclusion

CVE-2023-28962 highlights the importance of secure authentication mechanisms and keeping systems up-to-date. By understanding the exploit details and implementing necessary security measures, users can protect their devices and networks from potential attackers.

Timeline

Published on: 04/17/2023 22:15:00 UTC