CVE-2023-35137 in NAS326
Summary
by MITRE • 11/30/2023
An improper authentication vulnerability in the authentication module of the Zyxel NAS326 firmware version V5.21(AAZF.14)C0 and NAS542 firmware version V5.21(ABAG.11)C0 could allow an unauthenticated attacker to obtain system information by sending a crafted URL to a vulnerable device.
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Analysis
by VulDB Data Team • 11/30/2023
The vulnerability identified as CVE-2023-35137 represents a critical improper authentication flaw within the Zyxel NAS326 and NAS542 network-attached storage devices running specific firmware versions. This weakness stems from inadequate validation mechanisms within the authentication module, creating a pathway for unauthorized access to sensitive system information. The vulnerability specifically affects firmware versions V5.21(AAZF.14)C0 for NAS326 and V5.21(ABAG.11)C0 for NAS542, indicating a targeted issue within these particular device models and their corresponding software implementations. The flaw allows an attacker to exploit the system through a simple crafted URL delivery method, eliminating the need for prior authentication credentials.
The technical implementation of this vulnerability demonstrates a classic authentication bypass mechanism where the device fails to properly verify the legitimacy of incoming requests. When an attacker sends a specially crafted URL to the vulnerable device, the authentication module does not adequately validate the request parameters, potentially allowing access to system information that should remain restricted to authenticated users. This type of flaw falls under CWE-287, which specifically addresses improper authentication issues in software systems. The vulnerability's exploitation pathway suggests a lack of proper input validation and request filtering mechanisms that should normally be present in secure authentication modules.
From an operational impact perspective, this vulnerability presents significant security risks to organizations relying on Zyxel NAS devices for storage and data management. An unauthenticated attacker could potentially gain access to sensitive system information including device configuration details, user accounts, network settings, and potentially other system metadata that could be leveraged for further attacks. The low complexity of exploitation, requiring only a crafted URL delivery, makes this vulnerability particularly dangerous as it can be exploited remotely without requiring physical access or existing credentials. This characteristic aligns with ATT&CK technique T1078.004, which covers valid accounts used for lateral movement, as the vulnerability essentially allows unauthorized access to system information that could facilitate further compromise.
The mitigation strategy for this vulnerability requires immediate firmware updates from Zyxel to address the authentication module flaws. Organizations should prioritize updating their affected NAS326 and NAS542 devices to the latest firmware versions that contain patches for this specific vulnerability. Additionally, network administrators should implement monitoring of network traffic for suspicious URL patterns that might indicate exploitation attempts. The vulnerability's nature suggests that implementing proper request validation and authentication checking mechanisms would be essential for preventing similar issues in the future. Security teams should also conduct thorough assessments of their network-attached storage infrastructure to identify any other potentially vulnerable devices running similar firmware versions that might be susceptible to similar authentication bypass attacks.