CVE-2017-16741 in FL SWITCH
Summary
by MITRE
An Information Exposure issue was discovered in PHOENIX CONTACT FL SWITCH 3xxx, 4xxx, and 48xxx Series products running firmware Version 1.0 to 1.32. A remote unauthenticated attacker may be able to use Monitor Mode on the device to read diagnostic information.
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Analysis
by VulDB Data Team • 12/22/2019
The vulnerability identified as CVE-2017-16741 represents a critical information exposure flaw affecting PHOENIX CONTACT FL SWITCH series industrial network devices. This security weakness exists within firmware versions 1.0 through 1.32 of the FL SWITCH 3xxx, 4xxx, and 48xxx product lines, creating a significant risk for industrial control systems and network infrastructure. The vulnerability stems from insufficient access controls within the device's monitoring functionality, specifically in the Monitor Mode implementation that allows unauthorized remote access to sensitive diagnostic data.
The technical flaw manifests through the improper implementation of authentication mechanisms within the device's diagnostic interface. When Monitor Mode is enabled, the system fails to properly validate user credentials or enforce access restrictions, enabling any remote attacker to establish connections and extract diagnostic information without requiring legitimate authentication. This represents a fundamental breakdown in the device's security architecture, as the monitoring functionality intended for authorized maintenance personnel becomes accessible to malicious actors. The vulnerability operates at the network protocol level, exploiting weaknesses in the device's session management and access control implementation.
The operational impact of this vulnerability extends beyond simple information disclosure, potentially compromising the integrity of industrial network operations. Remote attackers can access diagnostic data that may reveal network topology, device configurations, firmware versions, and operational parameters that could facilitate more sophisticated attacks. This information exposure creates opportunities for attackers to map network structures, identify vulnerable components, and plan targeted attacks against the industrial control systems. The implications are particularly severe for critical infrastructure environments where these switches serve as foundational network components, as the leaked diagnostic information could reveal attack vectors and system weaknesses that adversaries could exploit to disrupt operations or gain deeper system access.
The vulnerability aligns with CWE-200, which addresses "Information Exposure," and represents a classic case of insufficient access control mechanisms. From an attack perspective, this issue maps to multiple ATT&CK tactics including reconnaissance and credential access, as attackers can gather intelligence about the target environment without requiring valid credentials. The lack of authentication checks in the Monitor Mode functionality creates a persistent security gap that remains exploitable across the affected firmware versions. Organizations utilizing these industrial switches should implement immediate mitigations including firmware updates, network segmentation, and disabling unnecessary monitoring interfaces to reduce the attack surface and prevent unauthorized access to sensitive diagnostic information.
The affected PHOENIX CONTACT devices operate within industrial environments where security is paramount, making this vulnerability particularly concerning. The combination of remote accessibility and information disclosure creates a pathway for attackers to conduct reconnaissance activities and gather intelligence for subsequent exploitation phases. This vulnerability highlights the importance of proper access control implementation in industrial network equipment and demonstrates how seemingly benign monitoring features can become security liabilities when not properly secured against unauthorized access attempts.