CVE-2007-3544 in WordPress
Summary
by MITRE
Unrestricted file upload vulnerability in (1) wp-app.php and (2) app.php in WordPress 2.2.1 and WordPress MU 1.2.3 allows remote authenticated users to upload and execute arbitrary PHP code via unspecified vectors, possibly related to the wp_postmeta table and the use of custom fields in normal (non-attachment) posts. NOTE: this issue reportedly exists because of an incomplete fix for CVE-2007-3543.
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Analysis
by VulDB Data Team • 09/05/2018
The vulnerability described in CVE-2007-3544 represents a critical unrestricted file upload flaw affecting WordPress 2.2.1 and WordPress MU 1.2.3 installations. This security weakness stems from inadequate validation mechanisms within the wp-app.php and app.php script files, which are part of the WordPress application programming interface. The vulnerability specifically targets authenticated users who possess sufficient privileges to create posts, making it particularly dangerous as it leverages legitimate user access to execute malicious code on the target system. The flaw operates by allowing attackers to upload PHP files through the WordPress post management interface, potentially bypassing standard security restrictions that should prevent execution of arbitrary code.
The technical exploitation of this vulnerability involves manipulating the wp_postmeta table structure and leveraging custom fields functionality within normal posts rather than attachment posts. This approach demonstrates how seemingly benign features can be weaponized when proper input validation and file type restrictions are absent. The vulnerability is particularly concerning because it was reportedly introduced due to an incomplete fix for CVE-2007-3543, indicating a pattern of security regressions where attempted patches fail to address all attack vectors. The use of custom fields in non-attachment posts creates an unexpected pathway for file uploads, as these fields typically store metadata associated with posts rather than executable content. This design flaw allows attackers to inject malicious PHP code into the post metadata, which can then be executed when the post is rendered or processed by the WordPress application.
The operational impact of this vulnerability extends beyond simple code execution to encompass full system compromise capabilities. Attackers can upload backdoor scripts, web shells, or other malicious payloads that persist on the server and provide ongoing access to the compromised WordPress installation. The vulnerability enables attackers to escalate privileges, steal sensitive data, modify content, or use the compromised server as a launching point for further attacks against other systems within the network. Given that WordPress installations often contain sensitive user data, configuration files, and database credentials, the potential for data breaches and system infiltration is substantial. The authenticated nature of this vulnerability means that attackers need only obtain legitimate user credentials or exploit other authentication bypasses to gain access to the upload functionality, making it particularly dangerous in environments where user accounts are not properly secured.
Mitigation strategies for CVE-2007-3544 should focus on immediate patching of affected WordPress versions, as the vulnerability was resolved in subsequent releases through proper input validation and file type restriction implementations. Organizations should implement strict file upload policies that validate file extensions, content types, and file signatures before allowing uploads to proceed. The implementation of Content Security Policies and proper file permission settings can further reduce the impact of successful exploitation attempts. Additionally, monitoring for unusual file upload activities and implementing web application firewalls can help detect and prevent exploitation attempts. This vulnerability aligns with CWE-434, which addresses the insecure upload of files, and maps to ATT&CK technique T1190 for exploiting vulnerabilities in web applications. Regular security audits and proper input sanitization practices should be implemented to prevent similar issues in other web applications, emphasizing the importance of comprehensive security testing and validation of security patches to avoid regression vulnerabilities that can compromise system integrity.