CVE-2017-14855 in HMI Panel
Summary
by MITRE
Red Lion HMI panels allow remote attackers to cause a denial of service (software exception) via an HTTP POST request to a long URI that does not exist, as demonstrated by version HMI 2.41 PLC 2.42.
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Analysis
by VulDB Data Team • 12/18/2019
The vulnerability identified as CVE-2017-14855 affects Red Lion HMI panels, specifically versions HMI 2.41 and PLC 2.42, presenting a significant security risk through a remote denial of service attack vector. This flaw resides within the web server implementation of the HMI panels, which fails to properly handle malformed HTTP requests, particularly those involving excessively long URI paths that do not correspond to existing resources. The vulnerability represents a classic example of insufficient input validation and error handling in network services, where the system does not adequately sanitize or process incoming HTTP requests before attempting to process them.
The technical exploitation of this vulnerability occurs when a remote attacker crafts an HTTP POST request containing a URI that exceeds the system's acceptable length limits and does not correspond to any legitimate endpoint within the HMI panel's web interface. When the system receives such a malformed request, it attempts to process the request without proper bounds checking, leading to a software exception that causes the web server component to crash or become unresponsive. This behavior stems from inadequate exception handling mechanisms within the embedded web server implementation, where the system fails to gracefully handle malformed input and instead allows the exception to propagate and terminate the service.
The operational impact of this vulnerability extends beyond simple service disruption, as it can be leveraged to systematically deny access to critical human machine interface functionalities that operators rely upon for industrial process control. In industrial environments where Red Lion HMI panels are deployed for monitoring and control of manufacturing processes, power generation, or other critical infrastructure, such a denial of service condition can lead to significant operational disruptions, potentially affecting production quality, safety protocols, and overall system reliability. The vulnerability particularly affects environments where these panels are connected to the internet or exposed to untrusted network segments, as the attack can be executed remotely without requiring physical access to the device.
From a cybersecurity framework perspective, this vulnerability aligns with CWE-129, which addresses issues related to insufficient input validation, and represents a clear violation of secure coding practices for web application development. The ATT&CK framework categorizes this as a denial of service attack vector under the technique of "Resource Exhaustion" where the attacker consumes system resources through malformed input, causing legitimate users to lose access to services. The vulnerability also demonstrates characteristics of CWE-248, which deals with exposure of an exception to external parties, as the system's failure to properly handle exceptions leads to service termination rather than graceful error recovery.
Organizations should implement immediate mitigations including network segmentation to isolate affected HMI panels from untrusted networks, deployment of intrusion detection systems to monitor for unusual HTTP request patterns, and application of firmware updates provided by Red Lion to address the specific implementation flaw. The recommended approach involves configuring network access controls to limit HTTP access to only trusted administrative networks, implementing rate limiting on HTTP requests to prevent abuse, and establishing monitoring procedures to detect potential exploitation attempts. Additionally, system administrators should consider disabling unnecessary web services on the HMI panels when full functionality is not required, as this reduces the attack surface available to potential attackers. Regular vulnerability assessments and security audits should be conducted to ensure that similar input validation flaws are not present in other components of the industrial control system infrastructure.