CVE-2024-4927: Simple Online Bidding System RCE Flaw

CVE-2024-4927 Overview

A critical unrestricted file upload vulnerability has been identified in SourceCodester Simple Online Bidding System version 1.0. This vulnerability exists in the file /simple-online-bidding-system/admin/ajax.php?action=save_product and allows attackers to upload arbitrary files without proper validation or restrictions. The vulnerability can be exploited remotely, potentially enabling attackers to upload malicious scripts that could lead to remote code execution on the affected server.

Critical Impact

Attackers can remotely upload malicious files to vulnerable servers, potentially achieving remote code execution and full system compromise through the unvalidated file upload functionality.

Affected Products

• SourceCodester Simple Online Bidding System 1.0
• oretnom23 simple_online_bidding_system (CPE: cpe:2.3:a:oretnom23:simple_online_bidding_system:1.0:*:*:*:*:*:*:*)

Discovery Timeline

• 2024-05-16 - CVE-2024-4927 published to NVD
• 2024-12-09 - Last updated in NVD database

Technical Details for CVE-2024-4927

Vulnerability Analysis

This vulnerability is classified as CWE-434 (Unrestricted Upload of File with Dangerous Type). The affected endpoint ajax.php?action=save_product in the admin directory fails to properly validate uploaded files, allowing attackers to bypass security controls and upload arbitrary file types. This is particularly dangerous in PHP-based web applications, as uploading a PHP webshell could grant attackers the ability to execute arbitrary commands on the server.

The vulnerability can be exploited remotely without requiring prior authentication credentials. An attacker can craft a malicious request to the vulnerable endpoint, uploading files with dangerous extensions such as .php, .phtml, or other executable formats that the web server may interpret and execute.

Root Cause

The root cause of this vulnerability lies in the absence of proper file type validation and sanitization in the save_product action handler within ajax.php. The application fails to implement essential security controls including:

• File extension whitelisting to restrict uploads to safe file types
• MIME type validation to verify file content matches claimed type
• File content inspection to detect malicious payloads
• Secure file storage outside of web-accessible directories

Attack Vector

The attack can be launched remotely over the network. An attacker targeting this vulnerability would typically:

1. Identify a vulnerable instance of Simple Online Bidding System
2. Craft an HTTP POST request to the /simple-online-bidding-system/admin/ajax.php?action=save_product endpoint
3. Include a malicious file (such as a PHP webshell) in the upload payload
4. The server stores the file without proper validation
5. The attacker accesses the uploaded malicious file to execute arbitrary code

The exploit for this vulnerability has been publicly disclosed. Technical details and proof-of-concept information can be found in the GitHub CVE Resource and VulDB #264463.

Detection Methods for CVE-2024-4927

Indicators of Compromise

• Presence of unexpected PHP files or webshells in product upload directories
• HTTP POST requests to /simple-online-bidding-system/admin/ajax.php?action=save_product from external or unauthorized sources
• Newly created files with executable extensions (.php, .phtml, .php5) in upload folders
• Web server access logs showing requests to unusual file paths within upload directories

Detection Strategies

• Monitor web application logs for POST requests to the vulnerable ajax.php?action=save_product endpoint
• Implement file integrity monitoring on upload directories to detect unauthorized file additions
• Deploy web application firewall (WAF) rules to block requests containing executable file extensions in upload parameters
• Use SentinelOne Singularity to detect suspicious process execution patterns originating from web server directories

Monitoring Recommendations

• Enable verbose logging on the web server to capture all requests to the affected endpoint
• Configure alerts for any new PHP files created in web-accessible directories
• Monitor for unusual outbound network connections from the web server that may indicate webshell activity
• Implement real-time file system monitoring on the Simple Online Bidding System installation directory

How to Mitigate CVE-2024-4927

Immediate Actions Required

• Restrict access to the /admin/ajax.php endpoint to authenticated and authorized users only
• Implement IP-based access controls to limit administrative functionality to trusted networks
• Consider taking the application offline until a proper patch or fix can be implemented
• Review upload directories for any suspicious or unauthorized files and remove them immediately

Patch Information

No official vendor patch has been released for this vulnerability at the time of publication. Organizations using SourceCodester Simple Online Bidding System 1.0 should monitor the vendor's communications for security updates. Additional vulnerability details are available through VulDB CTI ID #264463.

Workarounds

• Implement server-side file upload validation that restricts uploads to specific safe file types (e.g., images only)
• Rename uploaded files using random, unique identifiers and store them without their original extensions
• Store uploaded files outside of the web root directory to prevent direct execution
• Configure the web server to disable script execution in upload directories using .htaccess or equivalent server configuration
• Deploy a Web Application Firewall (WAF) to filter malicious upload attempts

# Apache configuration to disable PHP execution in upload directories
# Add to .htaccess in the upload directory
<Directory /path/to/simple-online-bidding-system/uploads>
    php_flag engine off
    AddHandler default-handler .php .phtml .php3 .php4 .php5
    RemoveHandler .php .phtml .php3 .php4 .php5
</Directory>