CVE-2024-50473: Ajar in5 Embed RCE Vulnerability

CVE-2024-50473 Overview

CVE-2024-50473 is an Unrestricted Upload of File with Dangerous Type vulnerability (CWE-434) affecting the Ajar in5 Embed WordPress plugin developed by Ajar Productions. This vulnerability allows attackers to upload malicious web shells to vulnerable web servers, potentially leading to complete server compromise.

The flaw exists in the file upload functionality of the plugin, which fails to properly validate or restrict the types of files that can be uploaded. Attackers can exploit this weakness to upload executable scripts (such as PHP web shells) that, once accessed, provide remote command execution capabilities on the target server.

Critical Impact

Successful exploitation allows attackers to upload web shells, enabling unauthorized remote code execution and full server compromise on affected WordPress installations.

Affected Products

• Ajar in5 Embed WordPress Plugin version 3.1.3 and earlier
• WordPress installations running vulnerable versions of ajar-productions-in5-embed
• Web servers hosting affected WordPress sites

Discovery Timeline

• 2024-10-29 - CVE-2024-50473 published to NVD
• 2026-04-01 - Last updated in NVD database

Technical Details for CVE-2024-50473

Vulnerability Analysis

This vulnerability is classified as CWE-434 (Unrestricted Upload of File with Dangerous Type), a severe class of web application security flaws. The Ajar in5 Embed plugin, designed to help embed Adobe InDesign content exported with in5 into WordPress sites, contains insufficient file upload validation mechanisms.

The vulnerability is particularly concerning given its high EPSS score of 30.566% (96.7th percentile), indicating a significantly elevated probability of active exploitation compared to typical vulnerabilities. This places it among the most likely-to-be-exploited vulnerabilities in the current threat landscape.

Root Cause

The root cause of CVE-2024-50473 lies in the plugin's failure to implement proper server-side file type validation. The upload handling mechanism does not adequately verify:

• File extensions against an allowlist of safe file types
• MIME type validation through content inspection
• File content signatures (magic bytes) to detect mismatched extensions

Without these controls, the application accepts arbitrary files, including server-side scripts that the web server will execute when accessed directly.

Attack Vector

The attack vector for this vulnerability follows a typical web shell upload exploitation pattern. An attacker can leverage the plugin's upload functionality to deliver a malicious PHP file to the server. The upload mechanism accepts the file without validating whether its type poses a security risk.

Once the malicious file is uploaded to an accessible location within the web root, the attacker can request the file directly through a web browser or automated tool. The web server then executes the script with the privileges of the web server process, granting the attacker command execution capabilities.

The exploitation chain typically involves:

1. Crafting a PHP web shell with desired backdoor functionality
2. Uploading the malicious file through the vulnerable plugin endpoint
3. Determining or guessing the uploaded file's path on the server
4. Accessing the web shell URL to gain remote command execution
5. Pivoting to further compromise the server, database, or network

Detection Methods for CVE-2024-50473

Indicators of Compromise

• Presence of unexpected PHP files in WordPress upload directories, particularly with suspicious names or recent modification dates
• Web server access logs showing requests to unusual PHP files in plugin or upload directories
• Unexpected outbound network connections originating from the web server process
• File system changes indicating creation of new executable files within the WordPress installation
• Anomalous process execution under the web server user account (www-data, apache, nginx)

Detection Strategies

• Monitor file uploads to WordPress directories for executable file types (.php, .phtml, .php5, etc.)
• Implement web application firewall (WAF) rules to block web shell signatures in upload requests
• Deploy file integrity monitoring (FIM) on WordPress installations to detect unauthorized file changes
• Review web server logs for POST requests to plugin upload endpoints followed by GET requests to newly created files

Monitoring Recommendations

• Enable detailed access logging on the web server with request body capture for upload endpoints
• Configure real-time alerting for new executable file creation in web-accessible directories
• Implement security information and event management (SIEM) correlation rules for web shell upload patterns
• Conduct regular malware scans of WordPress installations using reputable security plugins

How to Mitigate CVE-2024-50473

Immediate Actions Required

• Update the Ajar in5 Embed plugin to a patched version if available, or deactivate and remove the plugin until a fix is released
• Audit WordPress upload directories for any suspicious or unexpected files and remove unauthorized content
• Review web server access logs for evidence of exploitation attempts or successful compromise
• Implement restrictive file permissions on upload directories to prevent script execution
• Consider deploying a web application firewall with file upload inspection capabilities

Patch Information

Administrators should check the Patchstack Vulnerability Advisory for the latest patching guidance and version information. If no patched version is available, the plugin should be deactivated and removed from production environments.

Organizations should monitor vendor communications and security advisories for updates to the Ajar in5 Embed plugin addressing this vulnerability.

Workarounds

• Disable the vulnerable plugin entirely until a security patch is released
• Implement server-level controls to prevent PHP execution in upload directories using .htaccess or web server configuration
• Deploy a WAF rule to block file upload requests containing PHP content or script tags
• Restrict access to the plugin's upload functionality through authentication or IP-based access controls
• Use a reverse proxy to inspect and filter file uploads before they reach the WordPress installation

# Apache configuration to prevent PHP execution in uploads directory
# Add to .htaccess in wp-content/uploads/ or plugin upload directories
<FilesMatch "\.(?i:php|phtml|php3|php4|php5|phps)$">
    Order Deny,Allow
    Deny from all
</FilesMatch>

# Nginx configuration equivalent
# Add to server block or location context
location ~* /wp-content/uploads/.*\.php$ {
    deny all;
}