CVE-2012-3578 in FCChat Widget
Summary
by MITRE
Unrestricted file upload vulnerability in html/Upload.php in the FCChat Widget plugin 2.2.13.1 and earlier for WordPress allows remote attackers to execute arbitrary code by uploading a file with a file with an executable extension followed by a safe extension, then accessing it via a direct request to the file in html/images.
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Analysis
by VulDB Data Team • 06/12/2025
The CVE-2012-3578 vulnerability represents a critical unrestricted file upload flaw within the FCChat Widget plugin for WordPress, specifically affecting versions 2.2.13.1 and earlier. This vulnerability stems from inadequate input validation and sanitization mechanisms within the html/Upload.php file, which processes file uploads without proper restrictions on file extensions or content verification. The flaw allows malicious actors to bypass security measures by uploading files with executable extensions such as .php, .asp, or .jsp followed by seemingly harmless extensions like .jpg or .png, effectively creating a deceptive file naming scheme that can evade detection by basic security filters.
The technical exploitation of this vulnerability occurs through a sophisticated attack vector that leverages the plugin's file handling mechanism. Attackers can upload malicious payloads with carefully crafted filenames that appear legitimate to the system's security checks but contain executable code. When the system processes these uploads, it stores the files in the html/images directory with their original extensions, creating a situation where a file named shell.php.jpg would be stored with the .jpg extension but retain executable capabilities. This vulnerability directly maps to CWE-434, which describes the weakness of unrestricted upload of file with dangerous type, and aligns with ATT&CK technique T1190 for exploiting vulnerabilities in web applications through file upload mechanisms.
The operational impact of this vulnerability is severe and far-reaching, as it provides remote attackers with the capability to execute arbitrary code on the affected WordPress server. Once a malicious file is successfully uploaded and accessed, attackers can establish persistent backdoors, gain shell access, compromise the entire web application, or use the compromised server as a launch point for further attacks against the internal network. The vulnerability essentially transforms the WordPress installation into a potential command and control server, enabling attackers to perform reconnaissance, data exfiltration, and system manipulation. The attack can be executed entirely remotely without requiring any authentication credentials, making it particularly dangerous for WordPress installations that do not have proper network segmentation or additional security layers in place.
Mitigation strategies for CVE-2012-3578 must address both immediate remediation and long-term security hardening measures. The most critical action is to upgrade the FCChat Widget plugin to version 2.2.13.2 or later, where the vulnerability has been patched through improved file extension validation and content type checking. Organizations should implement comprehensive file upload restrictions that reject executable file types regardless of their extensions, enforce strict file content validation, and store uploaded files outside the web root directory to prevent direct execution. Additionally, implementing web application firewalls with file upload filtering capabilities, conducting regular security audits of installed plugins, and maintaining up-to-date security monitoring systems can significantly reduce the risk of exploitation. The vulnerability also highlights the importance of following secure coding practices such as those outlined in the OWASP Secure Coding Practices and adhering to the principle of least privilege when configuring file upload functionality in web applications.