CVE-2019-9951 in My Cloud
Summary
by MITRE
Western Digital My Cloud, My Cloud Mirror Gen2, My Cloud EX2 Ultra, My Cloud EX2100, My Cloud EX4100, My Cloud DL2100, My Cloud DL4100, My Cloud PR2100 and My Cloud PR4100 firmware before 2.31.174 is affected by an unauthenticated file upload vulnerability. The page web/jquery/uploader/uploadify.php can be accessed without any credentials, and allows uploading arbitrary files to any location on the attached storage.
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Analysis
by VulDB Data Team • 06/02/2020
The vulnerability identified as CVE-2019-9951 represents a critical unauthenticated file upload flaw affecting multiple Western Digital My Cloud storage devices including various models from the My Cloud series. This vulnerability stems from inadequate authentication mechanisms within the web interface, specifically targeting the uploadify.php endpoint that handles file uploads. The flaw allows any remote attacker to bypass authentication requirements and upload malicious files to the device's storage system without requiring valid credentials or administrative privileges. This represents a fundamental breakdown in the device's security architecture where the upload functionality lacks proper access controls and input validation measures. The affected firmware versions prior to 2.31.174 demonstrate a clear failure to implement proper authorization checks, creating an attack vector that directly violates security principle of least privilege.
The technical implementation of this vulnerability occurs through the web/jquery/uploader/uploadify.php script which serves as the entry point for file uploads. This endpoint accepts file uploads without requiring authentication, authentication tokens, or session validation. The vulnerability enables attackers to upload arbitrary files including executable scripts, malicious binaries, or web shells to any location on the attached storage devices. The lack of file type validation, directory traversal protections, and proper file extension checks creates an environment where attackers can upload malicious content that could be executed or accessed by the device's web server. This flaw directly maps to CWE-434 which defines insecure file upload vulnerabilities where applications accept untrusted files without proper validation and sanitization. The vulnerability also aligns with CWE-287 which addresses authentication failures in applications that do not properly verify user credentials or authorization levels.
The operational impact of this vulnerability is severe and multifaceted, as it provides attackers with direct persistence mechanisms and potential access to sensitive data stored on the network attached storage devices. Once exploited, attackers can upload web shells or backdoors that enable continuous unauthorized access to the device and its storage contents. The vulnerability allows for privilege escalation through file execution, potentially leading to complete system compromise and data exfiltration. Network security monitoring systems may not immediately detect malicious file uploads as they appear to be legitimate administrative operations. The affected devices represent valuable targets in enterprise and home network environments where they often store sensitive personal and business data. This vulnerability can be leveraged for lateral movement within networks, as compromised storage devices can serve as staging points for further attacks. The impact extends beyond simple data theft to include potential denial of service conditions if attackers upload malicious files that consume system resources or corrupt storage.
The attack surface for this vulnerability is particularly concerning given the widespread deployment of Western Digital My Cloud devices in both enterprise and home environments. Attackers can exploit this vulnerability through simple web requests without requiring specialized tools or deep technical knowledge, making it accessible to a broad range of threat actors. The vulnerability's exploitation does not require any specific network access conditions or advanced reconnaissance, as the upload endpoint is directly accessible. Security frameworks such as MITRE ATT&CK can categorize this vulnerability under T1195 for content injection attacks and T1078 for valid accounts usage, as attackers can leverage the legitimate upload functionality to establish persistent access. Organizations should implement immediate mitigation strategies including firmware updates to version 2.31.174 or later, network segmentation to isolate affected devices, and monitoring for suspicious file upload activities. Additional security controls such as web application firewalls, network access controls, and regular security audits should be implemented to prevent exploitation of this vulnerability and similar weaknesses in storage infrastructure.