CVE-2013-4338 in WordPress
Summary
by MITRE
wp-includes/functions.php in WordPress before 3.6.1 does not properly determine whether data has been serialized, which allows remote attackers to execute arbitrary code by triggering erroneous PHP unserialize operations.
If you want to get the best quality for vulnerability data then you always have to consider VulDB.
Analysis
by VulDB Data Team • 05/24/2021
The vulnerability identified as CVE-2013-4338 represents a critical deserialization flaw within the WordPress content management system that existed in versions prior to 3.6.1. This vulnerability resides in the wp-includes/functions.php file and specifically targets the serialization and unserialization processes that WordPress employs for data handling. The core issue stems from WordPress's inadequate validation of serialized data, creating a scenario where maliciously crafted input can bypass normal security checks and trigger unintended code execution.
The technical nature of this vulnerability falls under the category of insecure deserialization as classified by CWE-502, where the application accepts untrusted data and deserializes it without proper validation. When WordPress processes serialized data, it expects certain formatting and structure to maintain security boundaries. However, the flaw allows attackers to inject malformed serialized data that, when processed by the unserialize function, can execute arbitrary PHP code on the server. This occurs because the system fails to properly verify whether the data being processed represents legitimate serialized content or maliciously crafted input designed to exploit the deserialization mechanism.
The operational impact of this vulnerability is severe and multifaceted within the WordPress ecosystem. Attackers can leverage this weakness to execute arbitrary commands on vulnerable servers, potentially leading to complete system compromise, data exfiltration, and unauthorized access to sensitive information. The vulnerability's exploitation does not require authentication, making it particularly dangerous as it can be triggered through publicly accessible endpoints. This characteristic aligns with ATT&CK technique T1059.007 for command and script interpreter execution, where attackers can leverage the deserialization flaw to run malicious code on the target system. The vulnerability essentially provides a backdoor for remote code execution that can be exploited by anyone with access to the vulnerable WordPress installation.
This vulnerability demonstrates the critical importance of proper input validation and secure deserialization practices in web applications. The flaw highlights how seemingly innocuous data handling functions can become security gateways when insufficient validation is implemented. Organizations running affected WordPress versions face significant risk as this vulnerability can be exploited through various attack vectors including plugin and theme vulnerabilities, or by targeting exposed WordPress endpoints. The remediation strategy requires immediate patching to WordPress version 3.6.1 or later, which implements proper validation of serialized data before attempting deserialization operations. Additionally, implementing web application firewalls, input sanitization measures, and regular security audits can help mitigate the risk of similar vulnerabilities in other components of the WordPress ecosystem. The vulnerability serves as a prime example of why secure coding practices, particularly around data handling and validation, must be rigorously enforced in all software development processes to prevent such critical security breaches.