CVE-2024-3431: EyouCMS Deserialization RCE Vulnerability

CVE-2024-3431 Overview

A critical insecure deserialization vulnerability has been discovered in EyouCMS version 1.6.5. The vulnerability exists in the Backend component, specifically in the file /login.php?m=admin&c=Field&a=channel_edit. Manipulation of the channel_id argument leads to unsafe deserialization of user-supplied data, which can be exploited remotely by authenticated attackers to execute arbitrary code on the target system.

Critical Impact

This vulnerability allows authenticated remote attackers to achieve remote code execution through insecure deserialization in the EyouCMS backend administrative interface, potentially leading to complete system compromise.

Affected Products

• EyouCMS version 1.6.5

Discovery Timeline

• April 7, 2024 - CVE-2024-3431 published to NVD
• June 5, 2025 - Last updated in NVD database

Technical Details for CVE-2024-3431

Vulnerability Analysis

This vulnerability is classified as CWE-502 (Deserialization of Untrusted Data). The flaw exists within the administrative backend of EyouCMS, specifically in the channel editing functionality. When processing user-supplied input through the channel_id parameter, the application deserializes data without proper validation or sanitization.

Insecure deserialization occurs when an application accepts serialized objects from untrusted sources and reconstructs them without adequate security checks. In PHP applications like EyouCMS, this typically involves the unserialize() function processing attacker-controlled data, which can lead to object injection attacks.

The vulnerability requires authentication to the backend administrative panel, meaning an attacker would need valid credentials to exploit this flaw. However, once authenticated, the attacker can craft malicious serialized payloads that, when processed by the vulnerable endpoint, can trigger arbitrary code execution.

Root Cause

The root cause of this vulnerability is the improper handling of serialized data within the channel_edit action of the Field controller. The application fails to validate or sanitize the channel_id parameter before passing it to deserialization functions. This allows attackers to inject malicious serialized objects that can manipulate application logic or execute arbitrary code through PHP magic methods or gadget chains present in the application or its dependencies.

Attack Vector

The attack is initiated remotely over the network and requires low privilege access (authenticated user with backend access). The attacker targets the vulnerable endpoint at /login.php?m=admin&c=Field&a=channel_edit and supplies a crafted payload through the channel_id parameter. When the server deserializes this malicious input, it can trigger code execution through PHP object injection techniques.

The exploitation flow typically involves:

1. Authenticating to the EyouCMS administrative backend
2. Identifying available gadget chains within the application codebase
3. Crafting a serialized payload that leverages these gadgets
4. Sending the malicious payload through the channel_id parameter
5. Achieving arbitrary code execution when the payload is deserialized

For technical details on the exploitation mechanism, refer to the Notion RCE Report which documents the vulnerability.

Detection Methods for CVE-2024-3431

Indicators of Compromise

• HTTP requests to /login.php?m=admin&c=Field&a=channel_edit containing serialized PHP objects in the channel_id parameter
• Presence of unusual base64-encoded or URL-encoded serialized data in request parameters
• Web server logs showing repeated access attempts to the vulnerable endpoint with large or suspicious payloads
• Unexpected PHP processes or shell commands spawned by the web server process

Detection Strategies

• Implement Web Application Firewall (WAF) rules to detect serialized PHP objects in HTTP parameters
• Monitor for patterns indicative of PHP serialization (strings starting with O:, a:, s: in request parameters)
• Deploy intrusion detection signatures for known deserialization attack payloads
• Enable verbose logging on the EyouCMS backend to capture and analyze administrative actions

Monitoring Recommendations

• Review web server access logs for suspicious requests targeting /login.php?m=admin&c=Field&a=channel_edit
• Monitor for unauthorized changes to server files or configurations
• Implement file integrity monitoring on critical system and application directories
• Set up alerts for anomalous process execution from the web server context

How to Mitigate CVE-2024-3431

Immediate Actions Required

• Restrict access to the EyouCMS administrative backend to trusted IP addresses only
• Implement strong authentication mechanisms including multi-factor authentication for admin accounts
• Review and audit all administrative user accounts for unauthorized access
• Consider disabling or removing the vulnerable functionality until a patch is available

Patch Information

The vendor (EyouCMS) was contacted about this vulnerability but did not respond. As of the last modification date, no official patch has been released. Organizations using EyouCMS 1.6.5 should evaluate alternative mitigations or consider migrating to a different CMS platform. Monitor the VulDB entry and official EyouCMS channels for any future security updates.

Workarounds

• Implement network-level access controls to restrict backend access to authorized administrators only
• Deploy a Web Application Firewall configured to block serialized PHP objects in request parameters
• Consider placing the administrative interface behind a VPN to limit exposure
• Regularly audit backend user accounts and remove unnecessary administrative privileges

# Example: Restrict access to admin paths via .htaccess
<FilesMatch "login\.php">
    Order Deny,Allow
    Deny from all
    Allow from 192.168.1.0/24
    Allow from 10.0.0.0/8
</FilesMatch>