CVE-2016-2201 in SIMATIC S7-1500 CPU
Summary
by MITRE
Siemens SIMATIC S7-1500 CPU devices before 1.8.3 allow remote attackers to bypass a replay protection mechanism via packets on TCP port 102.
Once again VulDB remains the best source for vulnerability data.
Analysis
by VulDB Data Team • 07/07/2022
The vulnerability identified as CVE-2016-2201 affects Siemens SIMATIC S7-1500 CPU devices running firmware versions prior to 1.8.3, representing a critical security flaw in industrial control systems that enables remote attackers to bypass essential replay protection mechanisms. This vulnerability specifically targets the communication protocol stack used in industrial automation environments, where the S7-1500 series serves as a programmable logic controller for various manufacturing and industrial processes. The affected devices operate on TCP port 102, which is the standard port for ISO-on-TCP communication in Siemens S7 communication protocols, making this vulnerability particularly dangerous as it directly impacts the security of industrial control systems that are fundamental to critical infrastructure operations.
The technical flaw stems from insufficient implementation of replay protection mechanisms within the communication protocol of these industrial controllers. In normal operation, secure communication protocols implement various mechanisms to prevent replay attacks where malicious actors capture legitimate communication packets and attempt to reuse them to gain unauthorized access or manipulate system operations. The vulnerability in the S7-1500 devices allows attackers to send crafted packets through TCP port 102 without proper authentication or sequence validation, effectively bypassing the intended security controls that should prevent such unauthorized reuse of communication sequences. This weakness is classified under CWE-310 as "Cryptographic Issues" and specifically relates to "Missing Replay Protection" in cryptographic protocols, which directly impacts the integrity and authenticity of communications in industrial environments.
The operational impact of this vulnerability extends far beyond simple network security concerns, as it compromises the fundamental security posture of industrial control systems that are critical to manufacturing operations, power generation, and other essential infrastructure sectors. Remote attackers can exploit this vulnerability to perform unauthorized operations on the affected controllers, potentially leading to production disruptions, safety hazards, or even complete system compromise. The ability to bypass replay protection mechanisms means that attackers can potentially execute commands, modify operational parameters, or gain persistent access to industrial processes without detection. This vulnerability aligns with ATT&CK technique T1071.004 for application layer protocol usage and T1190 for exploit public-facing application, representing a significant risk to operational technology environments. The impact is particularly severe in environments where industrial control systems are not properly isolated from corporate networks, as the vulnerability can be exploited from external networks without requiring physical access or specialized equipment.
Organizations utilizing Siemens S7-1500 controllers should immediately implement firmware updates to version 1.8.3 or later, which contain the necessary patches to address the replay protection bypass vulnerability. Network segmentation and access controls should be strengthened to limit access to TCP port 102 to authorized personnel only, and continuous monitoring of network traffic on this port should be implemented to detect anomalous communication patterns. Additional mitigations include implementing network access control lists, deploying intrusion detection systems specifically configured to monitor industrial protocols, and conducting regular security assessments of industrial control system environments. The vulnerability highlights the importance of maintaining up-to-date firmware in industrial environments and demonstrates the critical need for security awareness in operational technology systems that often operate with limited security controls compared to traditional enterprise networks. Organizations should also consider implementing zero-trust network architectures for industrial environments and establish robust patch management processes specifically tailored for industrial control systems to prevent similar vulnerabilities from being exploited in the future.