CVE-2017-9938 in SIMATIC Logon
Summary
by MITRE
A vulnerability was discovered in Siemens SIMATIC Logon (All versions before V1.6) that could allow specially crafted packets sent to the SIMATIC Logon Remote Access service on port 16389/tcp to cause a Denial-of-Service condition. The service restarts automatically.
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Analysis
by VulDB Data Team • 12/15/2022
The vulnerability identified as CVE-2017-9938 affects Siemens SIMATIC Logon software versions prior to V1.6, presenting a significant security risk within industrial control systems environments. This flaw specifically targets the Remote Access service component that operates on TCP port 16389, making it particularly dangerous in operational technology infrastructure where system availability is critical. The vulnerability represents a classic denial-of-service condition that can be exploited through carefully crafted network packets, potentially disrupting critical industrial processes and manufacturing operations that depend on uninterrupted access to these systems.
The technical implementation of this vulnerability stems from insufficient input validation within the SIMATIC Logon service handling mechanism. When maliciously constructed packets are transmitted to the designated port 16389, the service fails to properly process these malformed inputs, resulting in an immediate system crash and subsequent automatic restart of the affected service. This behavior aligns with CWE-121, which addresses stack-based buffer overflow conditions, though the specific implementation appears to involve more general input validation failures that lead to service instability. The automatic restart functionality, while intended to restore service availability, creates a potential attack vector for sustained disruption through repeated exploitation attempts.
From an operational impact perspective, this vulnerability poses severe risks to industrial environments where uninterrupted system access is paramount for process control and safety operations. The automatic service restart mechanism, while providing some recovery capability, does not prevent the disruption of critical operations during the restart period, which can last several minutes depending on system configuration. The attack surface is particularly concerning given that industrial control systems often operate in isolated networks where traditional network monitoring tools may not be deployed, making detection of such attacks more challenging and potentially allowing for extended periods of service disruption without immediate detection.
The exploitation of this vulnerability aligns with tactics described in the MITRE ATT&CK framework under the Defense Evasion and Impact categories, specifically targeting service availability as a means of disrupting operations. Organizations implementing Siemens SIMATIC Logon systems in industrial environments should consider this vulnerability as part of their risk assessment for critical infrastructure protection. The vulnerability's impact extends beyond simple service interruption to potentially affect production schedules, safety systems, and overall operational continuity in manufacturing and process control environments. Security teams must evaluate their current monitoring capabilities to detect anomalous network traffic patterns on port 16389 and implement appropriate network segmentation strategies to limit exposure to this vulnerability. The recommended mitigation approach includes immediate deployment of the vendor-provided patch for SIMATIC Logon V1.6 or later versions, along with network access controls to restrict unauthorized access to the affected service port.