CVE-2024-13787: VEDA WordPress Theme RCE Vulnerability

CVE-2024-13787 Overview

The VEDA MultiPurpose WordPress Theme is vulnerable to PHP Object Injection in all versions up to and including 4.2. This vulnerability exists due to the deserialization of untrusted input in the veda_backup_and_restore_action function. Authenticated attackers with Subscriber-level access and above can exploit this flaw to inject arbitrary PHP objects into the application.

Critical Impact

While no known POP (Property-Oriented Programming) chain exists in the vulnerable theme itself, if another plugin or theme with a POP chain is installed on the same WordPress site, attackers could leverage this vulnerability to delete arbitrary files, retrieve sensitive data, or execute arbitrary code.

Affected Products

• VEDA - MultiPurpose WordPress Theme versions up to and including 4.2
• WordPress installations using the vulnerable VEDA theme versions
• Sites with additional plugins or themes containing POP chains (increased risk)

Discovery Timeline

• 2025-03-05 - CVE-2024-13787 published to NVD
• 2025-03-05 - Last updated in NVD database

Technical Details for CVE-2024-13787

Vulnerability Analysis

This vulnerability is classified as CWE-502 (Deserialization of Untrusted Data). The flaw resides in the veda_backup_and_restore_action function, which processes serialized data without proper validation. When the application deserializes user-controlled input, it can instantiate arbitrary PHP objects with attacker-controlled properties.

PHP Object Injection vulnerabilities become particularly dangerous when a POP chain is available in the codebase. A POP chain is a sequence of object method calls that, when triggered during deserialization (via magic methods like __wakeup(), __destruct(), or __toString()), can lead to dangerous operations such as file manipulation, database queries, or code execution.

Root Cause

The root cause is the use of PHP's unserialize() function on untrusted user input within the veda_backup_and_restore_action function. This function appears to handle backup and restore operations for the theme, where serialized data is processed without adequate sanitization or type checking. The theme fails to implement proper input validation or use safer alternatives like JSON encoding for data interchange.

Attack Vector

The attack is network-accessible and targets authenticated users with at least Subscriber-level privileges on the WordPress installation. An attacker would craft a malicious serialized PHP object payload and submit it through the backup/restore functionality. The exploitation flow typically involves:

1. Authenticating to the WordPress site with at least Subscriber privileges
2. Identifying endpoints that trigger the veda_backup_and_restore_action function
3. Crafting a serialized payload containing malicious object properties
4. Submitting the payload to exploit available POP chains in installed plugins or themes

The vulnerability mechanism involves unsafe deserialization in the backup and restore functionality. When user-controlled serialized data is passed to PHP's unserialize() function, it allows instantiation of arbitrary classes with attacker-controlled properties. Attackers can abuse magic methods that execute during deserialization to chain together method calls leading to dangerous operations. For detailed technical analysis, see the Wordfence Vulnerability Report.

Detection Methods for CVE-2024-13787

Indicators of Compromise

• Unusual or suspicious activity in WordPress backup/restore logs
• Unexpected file modifications or deletions, particularly in sensitive directories
• Web server logs showing POST requests to theme backup/restore endpoints with encoded or serialized data
• Database modifications or unauthorized data access attempts

Detection Strategies

• Monitor WordPress access logs for suspicious requests to VEDA theme endpoints containing serialized data patterns (e.g., O: prefix indicating PHP objects)
• Implement Web Application Firewall (WAF) rules to detect and block PHP serialization patterns in request parameters
• Deploy file integrity monitoring to detect unauthorized file changes that may result from successful exploitation
• Review user role assignments for unexpected Subscriber or higher-level accounts

Monitoring Recommendations

• Enable detailed logging for WordPress theme functions, particularly backup and restore operations
• Set up alerts for unusual activity from authenticated users with Subscriber-level access
• Monitor for the presence of newly installed plugins or themes that may introduce POP chains
• Implement runtime application self-protection (RASP) to detect deserialization attacks in real-time

How to Mitigate CVE-2024-13787

Immediate Actions Required

• Update the VEDA MultiPurpose WordPress Theme to a patched version as soon as one becomes available
• Audit installed plugins and themes for known POP chains that could be exploited in conjunction with this vulnerability
• Review user accounts and remove unnecessary Subscriber or higher-level accounts
• Implement WAF rules to block serialized PHP object patterns in incoming requests

Patch Information

Website administrators should check the ThemeForest Product Page for updated versions of the VEDA theme. Apply the latest security patches as they become available from the theme developer. Monitor the Wordfence Vulnerability Report for additional guidance and updates.

Workarounds

• Restrict access to the backup and restore functionality by limiting user roles that can access these features
• Temporarily disable the VEDA theme backup/restore functionality if not critically needed until a patch is available
• Implement application-level input filtering to sanitize or reject serialized PHP data in requests
• Consider using a security plugin that provides real-time protection against PHP Object Injection attacks

# Configuration example - WordPress .htaccess rule to block serialized object patterns
# Add to .htaccess to help mitigate serialization attacks
<IfModule mod_rewrite.c>
    RewriteEngine On
    RewriteCond %{QUERY_STRING} (O:|a:|s:) [NC,OR]
    RewriteCond %{REQUEST_BODY} (O:|a:|s:) [NC]
    RewriteRule .* - [F,L]
</IfModule>