CVE-2022-50893: VIAVIWEB Wallpaper Admin RCE Flaw

CVE-2022-50893 Overview

VIAVIWEB Wallpaper Admin 1.0 contains an unauthenticated remote code execution vulnerability in the image upload functionality. Attackers can upload a malicious PHP file through the add_gallery_image.php endpoint to execute arbitrary code on the server. This vulnerability is classified under CWE-434 (Unrestricted Upload of File with Dangerous Type), allowing attackers to bypass security controls and gain complete control over affected systems.

Critical Impact

This unauthenticated RCE vulnerability allows remote attackers to execute arbitrary code on the server without any authentication, potentially leading to complete system compromise, data theft, and lateral movement within the network.

Affected Products

• VIAVIWEB Wallpaper Admin 1.0

Discovery Timeline

• 2026-01-13 - CVE CVE-2022-50893 published to NVD
• 2026-01-13 - Last updated in NVD database

Technical Details for CVE-2022-50893

Vulnerability Analysis

This vulnerability exists due to inadequate file type validation in the image upload functionality of VIAVIWEB Wallpaper Admin 1.0. The add_gallery_image.php endpoint fails to properly verify that uploaded files are legitimate image files, allowing attackers to upload PHP scripts disguised as images or with PHP extensions directly.

The lack of authentication on this endpoint compounds the severity, as any remote attacker can exploit this vulnerability without needing valid credentials. Once a malicious PHP file is uploaded to the server, the attacker can access it via a web request to execute arbitrary commands with the privileges of the web server process.

Root Cause

The root cause of this vulnerability is the absence of proper input validation and file type verification in the image upload functionality. Specifically:

• The add_gallery_image.php endpoint does not require authentication
• File extension validation is either missing or can be bypassed
• The application does not verify file contents (magic bytes) to ensure uploaded files are legitimate images
• Uploaded files are stored in a web-accessible directory with executable permissions

Attack Vector

The attack leverages the network-accessible image upload endpoint. An attacker can craft a malicious PHP file containing a web shell or other executable code and upload it through the vulnerable endpoint. The attack sequence involves:

1. Identifying the vulnerable add_gallery_image.php endpoint
2. Crafting a PHP payload (e.g., web shell) with image extension or bypassing extension checks
3. Uploading the malicious file via HTTP POST request without authentication
4. Accessing the uploaded file through the web server to trigger code execution

The vulnerability is network-exploitable with no authentication required, making it trivial to exploit. Detailed technical information can be found in the Exploit-DB #51033 entry and the VulnCheck Advisory.

Detection Methods for CVE-2022-50893

Indicators of Compromise

• Unexpected PHP files appearing in image upload directories (e.g., uploads/, gallery/, images/)
• Web server access logs showing POST requests to add_gallery_image.php from unknown sources
• Unusual PHP files with image-like names (e.g., image.php, shell.jpg.php)
• Web server processes spawning child processes or executing system commands unexpectedly

Detection Strategies

• Monitor HTTP POST requests to add_gallery_image.php for suspicious file uploads
• Implement file integrity monitoring on web application directories to detect new PHP files
• Analyze web server logs for access patterns to recently uploaded files followed by command execution indicators
• Deploy web application firewall (WAF) rules to detect and block malicious file upload attempts

Monitoring Recommendations

• Enable detailed logging on the web server to capture all upload activity
• Implement real-time alerting for new executable file creation in web-accessible directories
• Monitor for unusual outbound network connections from the web server process
• Review process execution chains for the web server to detect command execution attempts

How to Mitigate CVE-2022-50893

Immediate Actions Required

• Restrict access to the add_gallery_image.php endpoint using firewall rules or .htaccess configuration
• Implement authentication requirements for all administrative upload functionality
• Remove or disable the VIAVIWEB Wallpaper Admin application if not essential to operations
• Audit upload directories for any suspicious PHP files that may have been uploaded

Patch Information

No official patch has been identified in the available CVE data. Organizations should contact Viavi Web directly to inquire about security updates. Until a patch is available, implement the workarounds described below to reduce exposure to this vulnerability.

Workarounds

• Block access to add_gallery_image.php at the web server or firewall level
• Implement strict file extension whitelisting to allow only genuine image formats (.jpg, .png, .gif)
• Configure the upload directory to prevent PHP execution using server configuration directives
• Deploy a web application firewall (WAF) with rules to detect and block malicious file uploads

# Apache configuration to prevent PHP execution in upload directory
<Directory /var/www/html/uploads>
    php_admin_flag engine off
    <FilesMatch "\.php$">
        Deny from all
    </FilesMatch>
</Directory>

# Block access to vulnerable endpoint
<Files "add_gallery_image.php">
    Deny from all
</Files>