CVE-2019-7684 in inxedu
Summary
by MITRE
inxedu through 2018-12-24 has a vulnerability that can lead to the upload of a malicious JSP file. The vulnerable code location is com.inxedu.os.common.controller.VideoUploadController#gok4 (com/inxedu/os/common/controller/VideoUploadController.java). The attacker uses the /video/uploadvideo fileType parameter to change the list of acceptable extensions from jpg,gif,png,jpeg to jpg,gif,png,jsp,jpeg.
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Analysis
by VulDB Data Team • 07/09/2023
The vulnerability identified as CVE-2019-7684 resides within the inxedu learning management system version 2018-12-24 and earlier, presenting a critical file upload restriction bypass that enables remote code execution through malicious JSP file uploads. This flaw exists in the VideoUploadController class at the gok4 method, specifically within the com/inxedu/os/common/controller/VideoUploadController.java file, where the application fails to properly validate file extensions during the upload process. The vulnerability stems from an insecure input validation mechanism that allows attackers to manipulate the acceptable file extensions by exploiting the fileType parameter in the /video/uploadvideo endpoint. When an attacker modifies the fileType parameter to include jsp among the accepted extensions, the system permits the upload of Java Server Pages files that can execute arbitrary code on the server, effectively transforming the legitimate video upload functionality into a weaponized attack vector.
The technical exploitation of this vulnerability follows a well-established pattern that aligns with CWE-434, which describes the weakness of unrestricted file upload allowing execution of malicious code. The attack begins with an attacker crafting a malicious JSP payload that typically contains commands to establish reverse shells, execute system commands, or perform data exfiltration. The vulnerability operates at the application layer, specifically targeting the file validation logic within the controller component of the web application architecture. The system's trust in user-provided parameters without proper sanitization creates an entry point where the attacker can effectively bypass the intended security controls that were designed to restrict uploads to image files only. This flaw demonstrates a classic example of insufficient input validation, where the application fails to implement proper access controls and content validation before accepting file uploads, making it susceptible to malicious file injection attacks.
The operational impact of this vulnerability extends far beyond simple unauthorized file uploads, as it provides attackers with persistent access to the underlying server infrastructure. Once successfully exploited, the malicious JSP file can be executed by the web server, enabling attackers to perform various malicious activities including but not limited to remote code execution, privilege escalation, data theft, and establishment of persistent backdoors. The vulnerability affects the entire application stack since it operates at the web application level where the file upload functionality is processed, potentially compromising all data stored within the inxedu system and exposing the underlying server to further attacks. Organizations using this vulnerable software face significant risks including regulatory compliance violations, data breaches, and potential system compromise that could lead to complete infrastructure takeover. The attack vector is particularly concerning because it requires minimal skill to exploit and can be automated, making it attractive to both opportunistic attackers and more sophisticated threat actors.
Mitigation strategies for this vulnerability should focus on immediate implementation of proper input validation and file extension filtering mechanisms within the application layer. Organizations should implement a whitelist-based approach for file extensions, ensuring that only explicitly allowed file types are accepted for upload, and never rely on blacklisting methods that can be easily bypassed. The system should enforce strict content validation by examining file headers and MIME types in addition to extension checks, as attackers often attempt to circumvent extension-based restrictions by renaming files. Security patches should be applied immediately to update the inxedu software to versions that address this vulnerability, while organizations should also implement network-level controls such as web application firewalls to detect and block suspicious upload attempts. Additionally, the principle of least privilege should be enforced by running the web application with minimal necessary permissions and implementing proper access controls to limit the impact of potential compromise. The vulnerability's classification under ATT&CK technique T1190 (Exploit Public-Facing Application) and CWE-434 demonstrates the need for comprehensive security measures including regular security assessments, proper code review processes, and incident response planning to address such critical vulnerabilities in enterprise web applications.