CVE-2016-4503 in 5232-N
Summary
by MITRE
Moxa Device Server Web Console 5232-N allows remote attackers to bypass authentication, and consequently modify settings and data, via vectors related to reading a cookie parameter containing a UserId value.
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Analysis
by VulDB Data Team • 03/15/2019
The CVE-2016-4503 vulnerability affects Moxa Device Server Web Console version 5232-N, representing a critical authentication bypass flaw that compromises the security posture of industrial network devices. This vulnerability resides within the web-based management interface of the device server, where improper handling of cookie parameters creates a pathway for unauthenticated attackers to gain administrative privileges. The flaw specifically manifests when the application reads a cookie parameter containing a UserId value without adequate validation or authentication checks, allowing malicious actors to manipulate this parameter and assume administrative roles within the system.
The technical implementation of this vulnerability stems from insufficient input validation and authentication mechanisms within the web console's session management system. When users access the device server's web interface, the application typically sets a cookie containing session information including user identification details. However, in this case, the system fails to properly validate the UserId value contained within the cookie, enabling attackers to craft malicious cookie values that bypass the normal authentication flow. This weakness falls under the category of improper authentication handling, which aligns with CWE-287, improper authentication, and represents a significant deviation from secure coding practices that should enforce strict validation of all session identifiers and user credentials.
The operational impact of this vulnerability extends beyond simple unauthorized access, as it enables complete administrative control over the affected device server. Attackers who successfully exploit this vulnerability can modify network configurations, update firmware, access sensitive operational data, and potentially disrupt industrial processes managed by the device server. The remote nature of the attack means that threat actors do not require physical access or network proximity to exploit the flaw, making it particularly dangerous in industrial environments where such devices often operate in restricted network segments. This vulnerability directly maps to ATT&CK technique T1078.004, legitimate credentials, as attackers can leverage the bypassed authentication to operate with administrative privileges within the system.
Security implications of CVE-2016-4503 are particularly severe in industrial control systems and critical infrastructure environments where Moxa device servers are commonly deployed. The vulnerability undermines the fundamental security model of the device server, allowing attackers to potentially compromise entire network segments managed by these industrial devices. Organizations using affected Moxa systems should immediately implement mitigations including firmware updates from the vendor, network segmentation to limit access to the device server, and implementation of additional authentication layers. The vulnerability demonstrates the critical importance of proper session management and authentication validation in networked industrial devices, as inadequate security controls can lead to complete system compromise and potential operational disruptions. This flaw underscores the necessity for regular security assessments of industrial network equipment and highlights the risks associated with legacy systems that may not receive timely security updates.