CVE-2024-9593: Time Clock WordPress Plugin RCE Vulnerability

CVE-2024-9593 Overview

CVE-2024-9593 is a Remote Code Execution (RCE) vulnerability affecting the Time Clock and Time Clock Pro plugins for WordPress. The vulnerability exists in the etimeclockwp_load_function_callback function, which allows unauthenticated attackers to execute arbitrary code on vulnerable WordPress servers. This critical flaw enables attackers to potentially take complete control of affected websites without requiring any authentication credentials.

Critical Impact

Unauthenticated remote code execution allows attackers to compromise WordPress servers running vulnerable Time Clock plugin versions, potentially leading to data theft, malware deployment, and complete site takeover.

Affected Products

• Time Clock plugin for WordPress versions up to and including 1.2.2
• Time Clock Pro plugin for WordPress versions up to and including 1.1.4
• All WordPress installations with vulnerable Time Clock plugin versions enabled

Discovery Timeline

• 2024-10-18 - CVE-2024-9593 published to NVD
• 2024-10-29 - Last updated in NVD database

Technical Details for CVE-2024-9593

Vulnerability Analysis

This vulnerability is classified as CWE-94 (Improper Control of Generation of Code, or Code Injection). The flaw resides in the etimeclockwp_load_function_callback function within the plugin's AJAX handler code. What makes this vulnerability particularly dangerous is that it requires no authentication—any remote attacker can trigger the vulnerable function over the network. The attack complexity is low, making exploitation straightforward for threat actors. While the invoked function's parameters cannot be specified by the attacker, the ability to execute arbitrary functions on the server still presents significant risk, enabling confidentiality, integrity, and availability impacts on the affected system and potentially cross-boundary effects on other resources.

Root Cause

The root cause of this vulnerability lies in improper input validation and code injection controls within the etimeclockwp_load_function_callback function. The plugin fails to adequately restrict which functions can be invoked through the AJAX callback mechanism, allowing attackers to call arbitrary PHP functions. This represents a fundamental security design flaw where user-controllable input is used to determine code execution paths without proper sanitization or allowlisting.

Attack Vector

The attack is network-based and can be executed remotely without any user interaction. An unauthenticated attacker sends a specially crafted request to the WordPress AJAX handler endpoint, targeting the etimeclockwp_load_function_callback function. The vulnerable code path in ajax_functions_admin.php processes the request and executes the attacker-specified function. While the attacker cannot control the function parameters, the ability to invoke arbitrary functions still enables various malicious actions depending on the available functions in the WordPress environment.

The vulnerable code can be found in the WordPress Time Clock Code repository. The WordPress Time Clock Changeset shows the modifications made to address this vulnerability.

Detection Methods for CVE-2024-9593

Indicators of Compromise

• Unusual HTTP POST requests to WordPress AJAX endpoints (/wp-admin/admin-ajax.php) with suspicious action parameters
• Unexpected process spawning or command execution originating from the web server process
• Log entries showing requests to etimeclockwp_load_function_callback from external IP addresses
• New or modified files in the WordPress installation directory that were not part of a legitimate update

Detection Strategies

• Monitor WordPress AJAX request logs for anomalous activity targeting Time Clock plugin endpoints
• Implement Web Application Firewall (WAF) rules to detect and block requests attempting to invoke the vulnerable callback function
• Deploy endpoint detection solutions to identify unauthorized code execution on web servers
• Use file integrity monitoring to detect unexpected changes to WordPress core and plugin files

Monitoring Recommendations

• Enable detailed access logging for all WordPress AJAX endpoints and review regularly
• Configure alerting for any attempts to access known vulnerable plugin functions
• Monitor web server process behavior for signs of compromise such as unexpected network connections or child processes
• Review the Wordfence Vulnerability Analysis for additional threat intelligence and detection guidance

How to Mitigate CVE-2024-9593

Immediate Actions Required

• Update Time Clock plugin to version 1.2.3 or later immediately
• Update Time Clock Pro plugin to version 1.1.5 or later immediately
• If updates cannot be applied immediately, deactivate and remove the affected plugins from your WordPress installation
• Conduct a security audit of any WordPress sites that had vulnerable versions installed to check for signs of compromise

Patch Information

The vulnerability has been addressed in Time Clock plugin version 1.2.3 and Time Clock Pro version 1.1.5. The patch implements proper input validation and restricts the functions that can be invoked through the AJAX callback mechanism. Administrators should update to the patched versions through the WordPress plugin update mechanism or by downloading the latest version from the WordPress plugin repository. The specific changes can be reviewed in the WordPress Time Clock Changeset.

Workarounds

• Completely deactivate and remove the Time Clock or Time Clock Pro plugin until the patched version can be installed
• Implement WAF rules to block requests containing the etimeclockwp_load_function_callback action parameter
• Restrict access to wp-admin/admin-ajax.php to authenticated users only if the plugin functionality is not required for public-facing features
• Consider using an alternative time tracking solution until the vulnerability is patched in your environment

# Disable vulnerable plugin via WP-CLI
wp plugin deactivate time-clock --path=/var/www/html/wordpress

# Update to patched version when available
wp plugin update time-clock --path=/var/www/html/wordpress

# Verify plugin version after update
wp plugin list --path=/var/www/html/wordpress | grep time-clock