CVE-2015-2177 in SIMATIC S7-300 Cpu
Summary
by MITRE
Siemens SIMATIC S7-300 CPU devices allow remote attackers to cause a denial of service (defect-mode transition) via crafted packets on (1) TCP port 102 or (2) Profibus.
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Analysis
by VulDB Data Team • 06/03/2026
The vulnerability identified as CVE-2015-2177 affects Siemens SIMATIC S7-300 CPU devices, which are widely deployed in industrial control systems and supervisory control and data acquisition environments. These devices operate as critical components in manufacturing and infrastructure automation, making their reliability and security paramount to operational continuity. The flaw manifests as a remote denial of service condition that can force the affected CPU devices into a defect mode transition, effectively rendering them non-functional within the industrial network. This vulnerability specifically targets the communication protocols used by these devices, creating a significant risk for industrial environments where continuous operation is essential.
The technical implementation of this vulnerability exploits weaknesses in the processing of network packets on two primary communication channels. The first attack vector utilizes TCP port 102, which is the standard port for S7 communication protocol used in Siemens industrial automation systems. The second vector targets the Profibus protocol, a widely used fieldbus communication standard in industrial automation that operates at the physical and data link layers of the OSI model. Attackers can craft malicious packets that, when transmitted to these specific ports, trigger unexpected behavior in the CPU device's protocol handling mechanisms. This occurs because the devices lack proper input validation and error handling for malformed or specially constructed packets, allowing the crafted data to disrupt normal operational flow and force the system into a defect state.
The operational impact of this vulnerability extends beyond simple service disruption, as it can compromise entire industrial control processes that depend on these devices for real-time monitoring and control. When an S7-300 CPU device transitions to defect mode, it typically ceases normal communication functions and may require manual intervention to restore operation, potentially causing production halts, safety system failures, or cascading effects throughout connected industrial processes. The remote nature of the attack means that adversaries can exploit this vulnerability from outside the industrial network perimeter, potentially targeting critical infrastructure without physical access. This vulnerability directly relates to CWE-129, which addresses improper validation of input boundaries, and aligns with ATT&CK technique T1499.001 for network denial of service attacks, demonstrating how industrial control systems face similar threats to traditional IT environments but with potentially more severe consequences.
Mitigation strategies for this vulnerability should focus on network segmentation and access control measures to limit exposure of these critical devices to untrusted networks. Implementing network filters to block unauthorized access to TCP port 102 and Profibus communication channels can significantly reduce attack surface. Organizations should also deploy intrusion detection systems specifically configured to monitor for anomalous packet patterns on these ports and establish regular firmware update schedules to ensure devices receive the latest security patches from Siemens. Additionally, implementing network monitoring solutions that can detect defect mode transitions and alert operators to potential attacks will help maintain operational awareness and enable rapid response to security incidents. The vulnerability underscores the importance of industrial network security practices and the need for continuous monitoring and protection of critical infrastructure components against remote exploitation attempts.