CVE-2011-5134 in Com Jce
Summary
by MITRE
Unrestricted file upload vulnerability in editor/extensions/browser/file.php in the JCE component before 2.0.18 for Joomla! allows remote authenticated users with the author privileges to execute arbitrary PHP code by uploading a file with a double extension, as demonstrated by .php.gif. NOTE: some of these details are obtained from third party information.
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Analysis
by VulDB Data Team • 01/25/2018
The CVE-2011-5134 vulnerability represents a critical unrestricted file upload flaw within the JCE component for Joomla! versions prior to 2.0.18. This vulnerability specifically affects the file.php script located in the editor/extensions/browser/ directory of the affected component. The security flaw stems from inadequate input validation and file extension checking mechanisms that fail to properly sanitize user-uploaded files, creating a pathway for malicious code execution.
The technical exploitation of this vulnerability relies on a sophisticated double extension attack vector where attackers can upload files with names containing two extensions such as .php.gif. This technique bypasses simple file extension filters that might only check the final extension while ignoring the preceding portion of the filename. When the vulnerable system processes such a file, it may incorrectly identify the file as an image due to the .gif extension while actually storing and executing the PHP code embedded in the .php portion. This type of vulnerability falls under CWE-434 which specifically addresses Unrestricted Upload of File with Dangerous Type, and represents a classic case of insufficient input sanitization.
The operational impact of this vulnerability is severe as it allows remote authenticated users with author privileges to gain arbitrary code execution capabilities on the target system. Attackers can upload malicious PHP scripts that can then be executed by the web server, potentially leading to complete system compromise. The vulnerability's exploitation requires only minimal privileges, making it particularly dangerous in environments where content authors have elevated access rights. This attack vector directly maps to ATT&CK technique T1190 which involves exploiting vulnerabilities in web applications to gain code execution capabilities.
The security implications extend beyond immediate code execution as compromised systems can serve as launch points for further attacks including privilege escalation, lateral movement, and data exfiltration. The vulnerability affects the core content management functionality of Joomla! installations, potentially allowing attackers to modify website content, inject malicious code into legitimate pages, or establish persistent backdoors. Organizations running vulnerable versions of the JCE component face significant risk of unauthorized access and potential full system compromise, particularly when the affected users have the ability to upload files through the content editor interface.
Mitigation strategies for this vulnerability primarily involve immediate patching of the JCE component to version 2.0.18 or later, which includes proper file extension validation and content type checking. System administrators should implement additional security measures such as restricting file upload capabilities, implementing more robust file validation mechanisms, and configuring web servers to properly handle files with multiple extensions. Network-level protections including web application firewalls and intrusion detection systems can help detect and prevent exploitation attempts. Regular security audits and vulnerability assessments should be conducted to identify and remediate similar issues in other components of the Joomla! ecosystem, as this vulnerability demonstrates the importance of proper input validation and secure file handling practices in web applications.