CVE-2016-7113 in SIPROTEC
Summary
by MITRE
The EN100 Ethernet module before 4.29 for Siemens SIPROTEC 4 and SIPROTEC Compact devices allows remote attackers to cause a denial of service (defect-mode transition) via crafted HTTP packets.
Several companies clearly confirm that VulDB is the primary source for best vulnerability data.
Analysis
by VulDB Data Team • 09/14/2022
The vulnerability identified as CVE-2016-7113 affects the EN100 Ethernet module in Siemens SIPROTEC 4 and SIPROTEC Compact protective relays, representing a significant security weakness that enables remote attackers to induce system-wide denial of service conditions. This issue specifically manifests through the manipulation of HTTP packet structures, allowing adversaries to trigger defect-mode transitions within the affected devices. The vulnerability resides in the module's insufficient input validation mechanisms, particularly when processing crafted HTTP requests that exploit the device's web server functionality. The affected systems operate in critical industrial environments where reliability and continuous operation are paramount, making this vulnerability particularly concerning for operational technology infrastructure. The EN100 Ethernet module serves as a communication interface for these protective relays, facilitating monitoring, configuration, and diagnostic functions through standard web protocols. When exploited, the vulnerability allows attackers to force the device into a defect mode state, effectively rendering the protective relay non-operational and potentially compromising the safety and reliability of the electrical systems it protects. This represents a direct violation of the availability principle in the CIA triad and can have cascading effects on power grid operations and industrial control systems.
The technical flaw stems from inadequate validation of HTTP request parameters within the web server implementation of the EN100 module, creating a path for input manipulation that leads to unauthorized state transitions. The vulnerability specifically targets the module's handling of malformed HTTP packets, where crafted payloads can cause the system to interpret certain request parameters as commands to initiate defect-mode operations. This weakness aligns with CWE-129, Input Validation, and CWE-20, Improper Input Validation, as the system fails to properly sanitize and validate incoming HTTP data before processing. The flaw operates at the application layer of the OSI model, specifically within the web server component that manages HTTP communications. Attackers can exploit this by sending specially crafted HTTP requests that manipulate internal state variables or trigger specific code paths within the module's firmware. The defect-mode transition represents a critical operational failure state where the device enters a non-functional condition, potentially leaving protective relays unable to perform their essential safety functions during power system disturbances. The vulnerability does not require authentication or specialized privileges to exploit, making it particularly dangerous as it can be triggered remotely from any network location with access to the device's web interface.
The operational impact of CVE-2016-7113 extends far beyond simple service disruption, as it can compromise the fundamental safety and reliability of industrial control systems that depend on SIPROTEC protective relays. In power grid environments, where these devices protect critical infrastructure such as transformers, switchgear, and transmission lines, a successful exploit can lead to complete loss of protective functionality during fault conditions, potentially resulting in equipment damage, power outages, or even safety hazards. The vulnerability's remote nature means that attackers can target these devices from external networks, potentially from anywhere in the world, without requiring physical access or network proximity. This makes the attack surface extremely broad and difficult to monitor or control. The defect-mode transition can occur without any visible indication to operators, as the device may silently enter this non-operational state, leaving system administrators unaware of the compromise until critical failures occur. The impact is particularly severe in environments where these devices are part of larger control systems, as the failure of individual protective relays can trigger cascading failures throughout the electrical network. The vulnerability also creates opportunities for more sophisticated attacks, as the initial denial of service can be used as a precursor to other malicious activities or as a method to mask additional attacks within the network. The potential for this vulnerability to be combined with other exploits to create more complex attack scenarios further amplifies its threat level.
Mitigation strategies for CVE-2016-7113 should focus on both immediate protective measures and long-term architectural improvements to secure industrial control systems. The most effective immediate solution is to upgrade the EN100 Ethernet module firmware to version 4.29 or later, which includes patches addressing the input validation issues that enable the vulnerability. Organizations should implement network segmentation to isolate these devices from general network access, reducing the attack surface and limiting potential exploit paths. Access controls should be enforced through secure authentication mechanisms, and unnecessary web server functionality should be disabled when not required for operational purposes. Network monitoring solutions should be deployed to detect anomalous HTTP traffic patterns that may indicate exploitation attempts, including unusual request frequencies or malformed packet structures. Regular security assessments and vulnerability scanning should be conducted to identify similar weaknesses in other components of the industrial control system. The implementation of network intrusion detection systems specifically designed for industrial environments can help detect and alert on suspicious activities targeting these protective devices. Additionally, organizations should develop incident response procedures that account for the specific threat landscape of industrial control systems, ensuring that operators know how to respond when devices enter defect modes. Compliance with industrial security standards such as IEC 62443 and NIST SP 800-82 should be maintained to provide comprehensive security frameworks that address vulnerabilities like CVE-2016-7113. The vulnerability also highlights the importance of maintaining up-to-date security patches for industrial equipment, as the affected devices were released before many modern security practices were established in industrial environments. Organizations should establish continuous monitoring programs that track security advisories from vendors and security researchers to proactively address similar vulnerabilities in their operational technology infrastructure.