CVE-2015-4463 in eFront
Summary
by MITRE
Unrestricted file upload vulnerability in eFront CMS before 3.6.15.5 allows remote authenticated users to execute arbitrary code by uploading a file with an executable extension prepended to a crafted parameter, then accessing it via a direct request to the file in www/content/lessons/"lesson number"/"directory name".
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Analysis
by VulDB Data Team • 11/01/2019
The CVE-2015-4463 vulnerability represents a critical unrestricted file upload flaw in the eFront Content Management System affecting versions prior to 3.6.15.5. This vulnerability specifically targets the file upload functionality within the platform's lesson management system, creating a pathway for remote authenticated attackers to escalate privileges and execute arbitrary code on the affected server. The vulnerability stems from inadequate input validation and sanitization mechanisms that fail to properly restrict file types and extensions, allowing malicious users to bypass security controls through sophisticated attack vectors.
The technical exploitation of this vulnerability involves a multi-step process where authenticated users leverage the platform's file upload functionality to place malicious files within the www/content/lessons/ directory structure. Attackers craft parameter names with executable extensions such as .php, .asp, or .jsp prepended to their upload requests, effectively bypassing standard file type checks that are typically implemented to prevent the upload of potentially harmful files. The system's failure to properly validate the file extensions and content results in these malicious files being stored in the web root directory, making them directly accessible through HTTP requests.
The operational impact of this vulnerability extends beyond simple code execution, as it provides attackers with persistent access to the compromised system. Once a malicious file is uploaded and executed, attackers can establish backdoors, escalate privileges, access sensitive data, and potentially use the compromised server as a launch point for further attacks within the network. The vulnerability affects the integrity and availability of the eFront platform, as it allows unauthorized modification of system files and can lead to complete system compromise. The direct accessibility of uploaded files through the www/content/lessons/ path means that attackers do not need additional exploitation techniques to achieve their objectives.
Security professionals should note that this vulnerability aligns with CWE-434, which specifically addresses the improper restriction of uploads of executable code, and demonstrates characteristics consistent with ATT&CK technique T1190 for exploiting vulnerabilities in web applications. The vulnerability's exploitation requires authentication, which reduces the attack surface compared to fully unauthenticated exploits, but still represents a significant risk to organizations using affected versions of eFront. Organizations should immediately implement mitigations including proper input validation, file type restrictions, and access controls to prevent unauthorized file uploads. The recommended solution involves patching the eFront platform to version 3.6.15.5 or later, which includes proper validation and sanitization of uploaded files, along with implementing additional security measures such as restricting write permissions to upload directories and monitoring for suspicious file upload activities.
This vulnerability highlights the critical importance of proper file upload validation in web applications and demonstrates how seemingly minor implementation flaws can lead to complete system compromise. The attack vector specifically targets the lesson content management functionality, indicating that organizations should review their content management systems for similar vulnerabilities in other upload mechanisms. The vulnerability also underscores the need for comprehensive security testing including penetration testing and code reviews to identify and remediate such flaws before they can be exploited by malicious actors. Organizations should implement defense-in-depth strategies including web application firewalls, regular security assessments, and proper access controls to protect against similar vulnerabilities in their web applications.