CVE-2019-9950 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 authentication bypass vulnerability. The login_mgr.cgi file checks credentials against /etc/shadow. However, the "nobody" account (which can be used to access the control panel API as a low-privilege logged-in user) has a default empty password, allowing an attacker to modify the My Cloud EX2 Ultra web page source code and obtain access to the My Cloud as a non-Admin My Cloud device user.
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Analysis
by VulDB Data Team • 06/02/2020
The vulnerability identified as CVE-2019-9950 affects a range of Western Digital My Cloud storage devices including various models from the EX2 Ultra to PR4100 series. This authentication bypass flaw stems from improper credential validation mechanisms within the firmware implementation, specifically within the login_mgr.cgi component that handles user authentication processes. The vulnerability represents a critical security weakness that undermines the device's access control framework and exposes sensitive system functionalities to unauthorized users.
The technical flaw manifests through the improper handling of the "nobody" account within the authentication system. This account, designed for low-privilege access to the control panel API, possesses a default empty password configuration that creates an exploitable entry point. The login_mgr.cgi script validates credentials against the /etc/shadow file but fails to properly secure or validate the nobody account's authentication state. This allows attackers to leverage the empty password to gain access to the web interface and subsequently manipulate the device's control panel functionality.
The operational impact of this vulnerability extends beyond simple unauthorized access, as it enables attackers to modify web page source code and gain access to the My Cloud device as a non-Admin user. This privilege escalation capability allows malicious actors to potentially compromise the storage integrity, access sensitive data, and manipulate device configurations. The vulnerability affects multiple device models across different generations, indicating a systemic flaw in the firmware authentication implementation that requires immediate remediation.
This vulnerability aligns with CWE-287 which addresses improper authentication issues in software systems. The flaw demonstrates poor access control implementation where default credentials are not properly secured or disabled, creating a persistent security weakness that attackers can exploit. From an ATT&CK framework perspective, this vulnerability maps to privilege escalation techniques and credential access methods, specifically targeting the T1110.003 sub-technique for credential access through brute force and default credentials. The attack surface is particularly concerning given that the vulnerability affects multiple device models and allows for code modification capabilities that could lead to further exploitation.
Mitigation strategies should focus on implementing firmware updates to version 2.31.174 or later, which address the authentication bypass vulnerability. Administrators should disable unused accounts including the nobody account when possible, and implement strong password policies for all active accounts. Network segmentation and access control measures should be deployed to limit exposure of these devices to untrusted networks. Regular security audits and vulnerability assessments should be conducted to identify similar authentication weaknesses in other networked storage devices and systems. The vulnerability highlights the importance of proper credential management and the need to avoid default empty passwords in authentication systems.