CVE-2024-49330: Nice Backgrounds RCE Vulnerability

CVE-2024-49330 Overview

CVE-2024-49330 is an unrestricted file upload vulnerability affecting the Nice Backgrounds WordPress plugin developed by brx8r. This vulnerability allows unauthenticated attackers to upload arbitrary files, including malicious web shells, to a vulnerable web server. The flaw stems from insufficient validation of uploaded file types, enabling attackers to bypass security controls and gain remote code execution capabilities on affected WordPress installations.

Critical Impact

Unauthenticated attackers can upload web shells to WordPress servers, potentially leading to complete site compromise, data theft, and use of the server for further attacks.

Affected Products

• brx8r Nice Backgrounds plugin version 1.0 and earlier
• WordPress installations running the Nice Backgrounds (nicebackgrounds) plugin

Discovery Timeline

• 2024-10-20 - CVE CVE-2024-49330 published to NVD
• 2026-04-01 - Last updated in NVD database

Technical Details for CVE-2024-49330

Vulnerability Analysis

This vulnerability is classified as CWE-434 (Unrestricted Upload of File with Dangerous Type). The Nice Backgrounds WordPress plugin fails to properly validate and sanitize file uploads, allowing attackers to upload files with dangerous extensions such as .php, .phtml, or other executable file types. Once uploaded, these malicious files can be accessed directly through the web server, resulting in arbitrary code execution in the context of the web application.

The attack can be conducted remotely over the network without requiring authentication or user interaction. An attacker who successfully exploits this vulnerability can achieve complete compromise of the affected WordPress installation, including access to sensitive configuration files (such as wp-config.php), database credentials, and the ability to modify site content or pivot to other systems on the network.

Root Cause

The root cause of this vulnerability lies in the plugin's failure to implement proper file upload validation controls. The Nice Backgrounds plugin does not adequately check:

• File extension against a whitelist of allowed types
• MIME type validation of uploaded content
• File content inspection to detect embedded malicious code

Without these security controls, the plugin accepts any file type submitted through the upload mechanism, including executable scripts that the web server will interpret and execute when accessed.

Attack Vector

The attack vector is network-based, requiring no authentication or user interaction. An attacker can craft a malicious HTTP request containing a web shell payload disguised or presented as a legitimate file upload. The typical attack flow involves:

1. Identifying a WordPress site running the vulnerable Nice Backgrounds plugin
2. Crafting an HTTP POST request to the plugin's file upload endpoint
3. Uploading a PHP web shell with a .php extension
4. Accessing the uploaded file directly via the web server to execute arbitrary commands

Since no authentication is required, this vulnerability is particularly dangerous for internet-facing WordPress installations. Once a web shell is uploaded, attackers can execute system commands, establish persistence, exfiltrate data, or use the compromised server as a staging point for additional attacks.

Detection Methods for CVE-2024-49330

Indicators of Compromise

• Unexpected PHP files or other executable scripts in WordPress upload directories (typically wp-content/uploads/)
• Web server access logs showing requests to suspicious files with PHP extensions in upload paths
• Unusual outbound network connections from the web server
• New or modified files in the nicebackgrounds plugin directory

Detection Strategies

• Monitor file system changes in WordPress upload directories for newly created PHP files
• Implement web application firewall (WAF) rules to detect and block file upload attempts with dangerous extensions
• Review web server access logs for POST requests to the Nice Backgrounds plugin upload endpoints followed by direct file access requests
• Deploy integrity monitoring solutions to detect unauthorized file modifications

Monitoring Recommendations

• Enable file integrity monitoring on WordPress installations, particularly in wp-content/uploads/ and plugin directories
• Configure alerting for any new executable files created in upload directories
• Monitor for suspicious HTTP requests containing common web shell signatures
• Implement network traffic analysis to detect command and control communications from compromised servers

How to Mitigate CVE-2024-49330

Immediate Actions Required

• Remove or deactivate the Nice Backgrounds plugin immediately from all WordPress installations
• Audit WordPress upload directories for any suspicious or unauthorized files
• Review web server access logs for evidence of exploitation attempts
• If compromise is suspected, perform a full security assessment and restore from known-good backups

Patch Information

No patch information is currently available from the vendor. Users are strongly advised to remove the Nice Backgrounds plugin until a security update is released. For additional details, refer to the Patchstack Vulnerability Report.

Workarounds

• Uninstall the Nice Backgrounds plugin completely until a patched version is available
• Implement server-level restrictions to prevent execution of PHP files in upload directories
• Deploy a web application firewall (WAF) with rules to block malicious file uploads
• Configure .htaccess rules to deny direct access to files in plugin upload directories

# Apache .htaccess configuration to prevent PHP execution in uploads directory
# Add this to wp-content/uploads/.htaccess
<FilesMatch "\.(?:php|phtml|php[3-7]|pht)$">
    Require all denied
</FilesMatch>