CVE-2018-16388 in e107
Summary
by MITRE
e107_web/js/plupload/upload.php in e107 2.1.8 allows remote attackers to execute arbitrary PHP code by uploading a .php filename with the image/jpeg content type.
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Analysis
by VulDB Data Team • 05/16/2023
The vulnerability identified as CVE-2018-16388 resides within the e107 content management system version 2.1.8, specifically in the file upload handling mechanism located at e107_web/js/plupload/upload.php. This flaw represents a critical security weakness that enables remote attackers to bypass file type validation controls and execute malicious PHP code on the target server. The vulnerability exploits a fundamental flaw in the application's file upload filtering process, where the system relies on content type headers rather than comprehensive file extension and MIME type verification.
The technical implementation of this vulnerability stems from improper input validation and sanitization within the file upload component. Attackers can manipulate the content type header to appear as image/jpeg while actually uploading a PHP file with a .php extension. This technique leverages the principle that many web applications accept file uploads based on MIME type headers without performing thorough file analysis. The flaw aligns with CWE-434, which describes insecure file upload vulnerabilities where applications accept files without proper validation of their actual content, and also relates to CWE-94, which covers improper control of generation of code, as the vulnerability allows for arbitrary code execution.
The operational impact of this vulnerability is severe and far-reaching for any organization using e107 2.1.8. Successful exploitation enables attackers to upload malicious PHP scripts that can be executed on the web server, potentially leading to complete system compromise. Attackers can leverage this vulnerability to establish persistent backdoors, steal sensitive data, deface websites, or use the compromised server as a launchpad for further attacks within the network. The vulnerability also aligns with several ATT&CK tactics including T1190 (Exploit Public-Facing Application) and T1059 (Command and Scripting Interpreter) as it allows for remote code execution through web application exploitation.
Mitigation strategies for this vulnerability require immediate action including upgrading to a patched version of e107, implementing comprehensive file type validation that checks both file extensions and actual file content, and deploying web application firewalls to detect and block suspicious upload attempts. Organizations should also implement proper file upload restrictions such as disabling PHP execution in upload directories, using random file naming schemes, and conducting thorough file content analysis using tools like file command or MIME type detectors. Additionally, network segmentation and monitoring of file upload activities can help detect potential exploitation attempts, while regular security audits should verify that all file upload mechanisms properly validate file content rather than relying solely on MIME type headers. The vulnerability demonstrates the critical importance of defense-in-depth strategies in web application security and highlights the necessity of comprehensive input validation controls that cannot be bypassed through simple header manipulation techniques.