CVE-2024-0739: Leadshop RCE Vulnerability

CVE-2024-0739 Overview

A critical insecure deserialization vulnerability was discovered in Hecheng Leadshop, an e-commerce platform. The vulnerability exists in the file /web/leadshop.php where the install parameter is improperly handled, allowing attackers to inject malicious serialized objects. This flaw enables remote attackers to execute arbitrary code on vulnerable systems without authentication, potentially leading to complete system compromise.

Critical Impact

Remote attackers can exploit this deserialization vulnerability to achieve arbitrary code execution on affected Leadshop installations, potentially compromising sensitive customer data and gaining full control of the web server.

Affected Products

• Hecheng Leadshop versions up to and including 1.4.20
• Leadshop e-commerce platform installations using vulnerable /web/leadshop.php endpoint

Discovery Timeline

• 2024-01-19 - CVE-2024-0739 published to NVD
• 2024-11-21 - Last updated in NVD database

Technical Details for CVE-2024-0739

Vulnerability Analysis

This vulnerability falls under CWE-502 (Deserialization of Untrusted Data), a severe class of security flaws where user-controllable data is deserialized without proper validation. In the case of Leadshop, the /web/leadshop.php file processes the install parameter through a deserialization routine that fails to validate or sanitize the incoming data before processing.

PHP deserialization vulnerabilities are particularly dangerous because they can trigger magic methods such as __wakeup(), __destruct(), or __toString() on arbitrary objects. When combined with available gadget chains in the application or its dependencies, this allows attackers to achieve Remote Code Execution (RCE) by crafting malicious serialized payloads.

The vulnerability has been publicly disclosed and exploit information is available, increasing the urgency for organizations running affected versions to apply patches or mitigations immediately.

Root Cause

The root cause of this vulnerability is the unsafe use of PHP's unserialize() function on user-supplied input from the install parameter without implementing proper validation or type restrictions. When untrusted serialized data is passed directly to unserialize(), attackers can instantiate arbitrary PHP objects present in the application's codebase, triggering dangerous operations through PHP's magic methods.

Attack Vector

The attack is network-based and can be executed remotely without authentication. An attacker crafts a malicious HTTP request containing a specially constructed serialized PHP object in the install parameter. When the vulnerable /web/leadshop.php endpoint deserializes this payload, the malicious object triggers a chain of method calls (POP chain) that ultimately results in arbitrary code execution.

The exploitation flow involves:

1. Identifying available gadget chains within Leadshop or its dependencies
2. Constructing a serialized payload that leverages these chains
3. Sending the payload via the install parameter to /web/leadshop.php
4. The application deserializes the payload, triggering the exploit chain

For technical details and proof-of-concept information, refer to the Zhaoj Note Security Summary and VulDB #251562.

Detection Methods for CVE-2024-0739

Indicators of Compromise

• Unusual HTTP POST requests to /web/leadshop.php containing the install parameter
• Presence of serialized PHP object strings (beginning with O:, a:, or s:) in request parameters
• Unexpected PHP process spawning or command execution originating from the web server
• Web server logs showing repeated access to /web/leadshop.php with large or encoded payloads

Detection Strategies

• Implement web application firewall (WAF) rules to detect and block requests containing PHP serialized object patterns in parameters
• Monitor web server access logs for suspicious requests targeting /web/leadshop.php with the install parameter
• Deploy endpoint detection solutions like SentinelOne to identify post-exploitation activities such as web shells or reverse shells
• Configure intrusion detection systems (IDS) to alert on common PHP deserialization exploit signatures

Monitoring Recommendations

• Enable detailed logging for the Leadshop application and web server to capture all requests to sensitive endpoints
• Set up real-time alerting for any requests containing serialized PHP data patterns
• Monitor system processes for anomalous child processes spawned by the web server user
• Regularly review file integrity monitoring alerts for unexpected changes in the web root directory

How to Mitigate CVE-2024-0739

Immediate Actions Required

• Upgrade Hecheng Leadshop to a patched version beyond 1.4.20 if available from the vendor
• If no patch is available, restrict access to /web/leadshop.php or disable the installation functionality
• Implement WAF rules to block requests containing serialized PHP objects in the install parameter
• Consider taking vulnerable Leadshop instances offline until a patch can be applied

Patch Information

At the time of this advisory, users should check the official Leadshop repository and vendor communications for security updates. Review the VulDB CTI #251562 for the latest vulnerability intelligence and remediation guidance.

Workarounds

• Block external access to /web/leadshop.php using web server configuration (.htaccess or nginx location blocks)
• Implement input validation at the application layer to reject serialized data in the install parameter
• Deploy a Web Application Firewall with rules targeting PHP deserialization attack patterns
• Restrict the install functionality to authenticated administrators only via IP whitelisting

# Example: Block access to vulnerable endpoint in Apache .htaccess
<Files "leadshop.php">
    <If "%{QUERY_STRING} =~ /install=/">
        Require all denied
    </If>
</Files>

# Example: Nginx configuration to block suspicious requests
location /web/leadshop.php {
    if ($args ~* "install=") {
        return 403;
    }
}