CVE-2017-16743 in FL SWITCH
Summary
by MITRE
An Improper Authorization 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 craft special HTTP requests allowing an attacker to bypass web-service authentication allowing the attacker to obtain administrative privileges on the device.
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Analysis
by VulDB Data Team • 12/22/2019
The vulnerability CVE-2017-16743 represents a critical improper authorization flaw in PHOENIX CONTACT FL SWITCH series industrial network devices. This weakness exists within firmware versions 1.0 through 1.32 of the 3xxx, 4xxx, and 48xxx product lines, creating a significant security risk for industrial control systems. The flaw allows remote attackers to bypass authentication mechanisms through specially crafted HTTP requests, fundamentally undermining the security model of these network switches. This issue is particularly concerning given the industrial nature of these devices, which typically operate in critical infrastructure environments where unauthorized access can lead to severe operational disruptions and safety hazards.
The technical implementation of this vulnerability stems from inadequate authorization checks within the web service interface of these industrial switches. When processing HTTP requests, the affected devices fail to properly validate authentication credentials before granting administrative access levels. This improper authorization mechanism enables attackers to construct malicious requests that circumvent the standard authentication flow, effectively allowing unauthenticated users to escalate their privileges to administrative status. The flaw likely resides in the web server component's handling of session management or access control tokens, where insufficient validation permits arbitrary privilege escalation through crafted request parameters.
The operational impact of this vulnerability extends beyond simple unauthorized access, creating a comprehensive security breach that could compromise entire industrial networks. Remote attackers with basic network connectivity can exploit this vulnerability without requiring physical access or legitimate credentials, making it particularly dangerous for industrial environments where such switches often serve as network gateways or core infrastructure components. Once administrative privileges are obtained, attackers can modify network configurations, access sensitive operational data, disable security features, or potentially cause network disruptions that could impact production processes. This vulnerability aligns with CWE-285, which specifically addresses improper authorization issues in software systems.
From a threat modeling perspective, this vulnerability maps directly to several ATT&CK techniques including T1078 for valid accounts usage and T1068 for exploit for privilege escalation. The remote nature of the attack means that adversaries can operate from outside the physical network perimeter, potentially using this vulnerability as a foothold for lateral movement within industrial networks. The affected devices typically serve as network switches in critical infrastructure, making this vulnerability particularly attractive to nation-state actors or organized cybercriminal groups targeting industrial control systems. Organizations should consider this vulnerability as part of broader industrial cybersecurity risk assessments, particularly in environments where these devices are deployed in operational technology networks.
The recommended mitigation strategy involves immediate firmware updates from PHOENIX CONTACT to address the authorization flaw in affected versions. Network administrators should also implement network segmentation to limit access to these devices, deploy intrusion detection systems to monitor for suspicious HTTP traffic patterns, and consider disabling unnecessary web services when not required for operational purposes. Additionally, organizations should conduct comprehensive inventory audits to identify all affected devices within their industrial control networks and establish monitoring procedures to detect potential exploitation attempts. The vulnerability demonstrates the importance of proper authorization implementation in industrial network devices and highlights the need for regular security assessments of operational technology infrastructure to prevent similar issues in the future.