CVE-2011-5004 in Com Fabrikar
Summary
by MITRE
Unrestricted file upload vulnerability in models/importcsv.php in the Fabrik (com_fabrik) component before 2.1.1 for Joomla! allows remote authenticated users with Manager privileges to execute arbitrary code by uploading a file with an executable extension, then accessing it via a direct request to the file in an unspecified directory.
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Analysis
by VulDB Data Team • 01/14/2018
The CVE-2011-5004 vulnerability represents a critical unrestricted file upload flaw within the Fabrik component for Joomla administrators and users. The flaw specifically targets authenticated users who possess Manager privileges, making it particularly dangerous as it leverages legitimate administrative access to escalate privileges and execute malicious code. The vulnerability stems from inadequate input validation and file extension filtering mechanisms within the import functionality, allowing attackers to bypass security controls designed to prevent execution of potentially harmful files.
The technical exploitation of this vulnerability follows a straightforward but dangerous methodology where authenticated users can upload malicious files with executable extensions such as php, asp, or other server-side script extensions. Once uploaded, these files can be executed by the web server when accessed directly through a web browser or other HTTP requests. The vulnerability's impact is amplified by the fact that the uploaded files are placed in an unspecified directory, making it difficult for administrators to predict or properly secure the upload locations. This design flaw creates a persistent backdoor that can be exploited repeatedly by attackers who maintain their Manager-level access. The vulnerability aligns with CWE-434, which specifically addresses the improper restriction of uploads of executable code, and represents a classic example of how insufficient validation can lead to arbitrary code execution.
The operational impact of CVE-2011-5004 extends far beyond simple file upload capabilities, as it provides attackers with complete control over the affected Joomla! installation. Once a malicious file is successfully uploaded and executed, attackers can perform various malicious activities including data exfiltration, privilege escalation, and establishing persistent access to the compromised system. The vulnerability enables attackers to potentially gain shell access, modify website content, steal sensitive data, and use the compromised server for further attacks against other systems. From an attacker's perspective, this vulnerability falls under the MITRE ATT&CK framework's technique T1059 for Command and Scripting Interpreter and T1566 for Phishing with Malicious Attachments, as it allows for the execution of arbitrary commands and the potential for further reconnaissance. The vulnerability also demonstrates the principle of least privilege violation, as it allows users with Manager roles to escalate their privileges beyond their intended scope.
Security mitigations for CVE-2011-5004 primarily focus on immediate patching and implementation of robust file upload controls. Organizations should immediately upgrade to Fabrik version 2.1.1 or later, which includes proper file extension validation and upload restrictions. Additionally, administrators should implement comprehensive file type filtering that rejects executable extensions and implements proper file validation mechanisms. The system should also enforce strict file upload directory permissions and ensure that uploaded files are stored outside the web root directory to prevent direct execution. Network-based mitigations include implementing web application firewalls that can detect and block suspicious file upload patterns, and monitoring for unusual file upload activities within the application. The vulnerability highlights the importance of following secure coding practices and implementing defense-in-depth strategies, as outlined in the OWASP Top Ten security principles, particularly focusing on input validation and secure file handling practices that prevent the execution of uploaded content.