CVE-2018-15696 in Data Master
Summary
by MITRE
ASUSTOR Data Master 3.1.5 and below allows authenticated remote non-administrative users to enumerate all user accounts via user.cgi.
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Analysis
by VulDB Data Team • 03/18/2020
The vulnerability identified as CVE-2018-15696 affects ASUSTOR Data Master versions 3.1.5 and earlier, representing a critical security flaw that undermines the authentication and authorization mechanisms of the affected system. This issue stems from improper access controls within the user.cgi component, which is designed to handle user-related operations but fails to adequately validate user permissions. The vulnerability specifically targets non-administrative users who are already authenticated within the system, creating a privilege escalation scenario that allows them to access information they should not normally be able to retrieve.
The technical implementation of this vulnerability resides in the user.cgi script which processes user enumeration requests without proper authorization checks. When an authenticated user sends a request to this component, the system fails to verify whether the requesting user has sufficient privileges to access the complete user account listing. This oversight creates a path for authenticated attackers to bypass normal access controls and obtain comprehensive information about all user accounts within the system. The flaw operates at the application layer and requires only valid login credentials to exploit, making it particularly dangerous as it can be leveraged by users who are already inside the system.
The operational impact of this vulnerability extends beyond simple information disclosure, as it provides attackers with detailed insights into the system's user infrastructure that can be used for further attacks. An attacker who gains access to the complete user account enumeration can identify administrative accounts, understand user hierarchy, and potentially identify weak passwords through pattern analysis. This information can be combined with other attack vectors to facilitate privilege escalation, credential stuffing attacks, or social engineering campaigns. The vulnerability affects the confidentiality aspect of the CIA triad by exposing sensitive user information that should remain private to authorized personnel only.
Security professionals should recognize this vulnerability as a classic example of insufficient access control, which aligns with CWE-285, or inadequate authorization, and can be categorized under the ATT&CK framework as privilege escalation techniques. The vulnerability demonstrates how seemingly minor authorization flaws can create significant security implications, particularly when they allow authenticated users to access information beyond their intended scope. Organizations should implement immediate mitigations including applying the vendor-provided patch, reviewing access control policies, and monitoring for unauthorized enumeration attempts. Additionally, network segmentation and monitoring of user.cgi access patterns can help detect potential exploitation attempts and provide early warning of compromise.
The remediation approach for this vulnerability requires immediate patch deployment from ASUSTOR, as the fix typically involves implementing proper authorization checks within the user.cgi component to ensure that only administrative users can access complete user account enumeration features. System administrators should also conduct comprehensive security reviews of all user management components to identify similar authorization gaps, while implementing proper logging and monitoring to detect unauthorized access attempts to user enumeration features. This vulnerability highlights the importance of least privilege principles and proper access control implementation in enterprise storage systems where user account information can be leveraged for broader attacks. Organizations should also consider implementing additional security controls such as account lockout mechanisms and multi-factor authentication to reduce the impact of credential compromise and prevent unauthorized enumeration attempts from succeeding.