CVE-2024-54367: ForumWP Object Injection Vulnerability

CVE-2024-54367 Overview

CVE-2024-54367 is an Insecure Deserialization vulnerability affecting the ForumWP plugin for WordPress. The vulnerability allows unauthenticated attackers to perform PHP Object Injection through the deserialization of untrusted data. This flaw exists in ForumWP versions up to and including 2.1.0 and can be exploited remotely without any user interaction or prior authentication.

Critical Impact

Unauthenticated attackers can exploit this PHP Object Injection vulnerability to potentially achieve remote code execution, manipulate application data, or compromise the underlying WordPress installation.

Affected Products

• ForumWP Free Plugin for WordPress (versions through 2.1.0)
• ForumWP Pro Plugin for WordPress (versions through 2.1.0)
• ultimatemember forumwp

Discovery Timeline

• 2024-12-16 - CVE-2024-54367 published to NVD
• 2025-02-05 - Last updated in NVD database

Technical Details for CVE-2024-54367

Vulnerability Analysis

This vulnerability stems from the improper handling of serialized PHP data within the ForumWP plugin. When user-supplied input containing serialized objects is processed by the application, it is deserialized without adequate validation or sanitization. This allows an attacker to inject malicious PHP objects that, when deserialized, can execute arbitrary code or perform other malicious actions depending on the available gadget chains within the WordPress environment and its installed plugins.

The vulnerability is classified under CWE-502 (Deserialization of Untrusted Data), which describes scenarios where applications deserialize data from untrusted sources without proper verification. In the context of WordPress plugins, PHP Object Injection vulnerabilities are particularly dangerous because the rich ecosystem of plugins and themes often provides numerous "magic methods" (such as __wakeup(), __destruct(), or __toString()) that can be chained together to achieve code execution.

Root Cause

The root cause of CVE-2024-54367 is the use of PHP's unserialize() function on user-controlled input without implementing proper safeguards. The ForumWP plugin fails to validate the integrity and source of serialized data before deserializing it, allowing attackers to craft malicious serialized payloads that instantiate arbitrary objects with attacker-controlled properties.

Attack Vector

The attack is conducted over the network and requires no authentication or user interaction. An attacker can submit a specially crafted HTTP request containing a malicious serialized PHP payload to the vulnerable ForumWP endpoint. Upon processing, the application deserializes the payload, instantiating the attacker's chosen objects.

The exploitation process typically involves:

1. Identifying an entry point where the plugin accepts and deserializes user input
2. Discovering available PHP classes with exploitable magic methods (gadget chains)
3. Constructing a serialized payload that chains these methods to achieve the desired outcome
4. Submitting the payload to the vulnerable endpoint

If suitable Property Oriented Programming (POP) chains exist in the WordPress core, ForumWP plugin, or other installed plugins, the attacker can leverage them to execute arbitrary PHP code, read sensitive files, establish persistence, or perform database operations.

Detection Methods for CVE-2024-54367

Indicators of Compromise

• Unusual HTTP requests to ForumWP plugin endpoints containing encoded or serialized data patterns (look for O: prefixes indicating PHP object serialization)
• Unexpected PHP errors or exceptions in logs related to object instantiation or class loading
• Web server logs showing requests with unusually long or base64-encoded POST parameters targeting ForumWP routes
• Signs of unauthorized file modifications, new backdoor files, or unexpected user accounts in WordPress

Detection Strategies

• Implement Web Application Firewall (WAF) rules to detect and block requests containing PHP serialized object patterns
• Monitor application logs for deserialization errors or unexpected class instantiation messages
• Deploy file integrity monitoring to detect unauthorized changes to WordPress core files, plugins, or themes
• Audit incoming HTTP requests for suspicious payloads containing serialized PHP object signatures

Monitoring Recommendations

• Enable verbose logging for the ForumWP plugin and review logs regularly for anomalies
• Configure real-time alerting for any detected PHP Object Injection attempts at the WAF level
• Implement endpoint detection and response (EDR) solutions to monitor for post-exploitation activities such as webshell deployment

How to Mitigate CVE-2024-54367

Immediate Actions Required

• Update ForumWP plugin immediately to a patched version beyond 2.1.0 if available
• If no patch is available, consider temporarily deactivating the ForumWP plugin until a fix is released
• Deploy WAF rules to block requests containing serialized PHP objects targeting ForumWP endpoints
• Review WordPress site for any indicators of compromise and remediate as necessary

Patch Information

Organizations using ForumWP should monitor the official plugin repository and the Patchstack Vulnerability Report for updates regarding security patches. Apply any available updates as soon as they are released. The vulnerability affects ForumWP versions from the earliest releases through 2.1.0, meaning all users of the plugin should verify their version and upgrade status.

Workarounds

• Temporarily disable the ForumWP plugin if it is not business-critical until a patch is available
• Implement strict input validation at the web server or reverse proxy level to reject requests with serialized PHP object patterns
• Restrict access to the WordPress admin area and plugin endpoints using IP allowlisting where feasible
• Deploy a virtual patching solution through a WAF to mitigate the vulnerability at the network perimeter

# Example: Block serialized PHP objects in Apache .htaccess
# Add to your WordPress root .htaccess file
<IfModule mod_rewrite.c>
RewriteEngine On
RewriteCond %{QUERY_STRING} (O:[0-9]+:) [NC,OR]
RewriteCond %{REQUEST_BODY} (O:[0-9]+:) [NC]
RewriteRule .* - [F,L]
</IfModule>