CVE-2016-7987 in SM-2558
Summary
by MITRE
An issue was discovered in Siemens ETA4 firmware (all versions prior to Revision 08) of the SM-2558 extension module for: SICAM AK, SICAM TM 1703, SICAM BC 1703, and SICAM AK 3. Specially crafted packets sent to Port 2404/TCP could cause the affected device to go into defect mode. A cold start might be required to recover the system, a Denial-of-Service Vulnerability.
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Analysis
by VulDB Data Team • 09/01/2020
The vulnerability identified as CVE-2016-7987 represents a critical denial-of-service weakness in Siemens ETA4 firmware versions prior to Revision 08 affecting multiple SICAM series devices including SICAM AK, SICAM TM 1703, SICAM BC 1703, and SICAM AK 3. This flaw resides within the SM-2558 extension module that operates on TCP port 2404, making it particularly concerning for industrial control systems where uninterrupted operation is paramount. The vulnerability stems from insufficient input validation mechanisms within the firmware's network protocol handling, specifically targeting the communication interface that manages industrial automation and control processes.
The technical exploitation of this vulnerability occurs through the transmission of specially crafted network packets to the designated TCP port 2404. These malformed packets trigger a condition where the affected device transitions into a defective operational state, effectively rendering the industrial control system non-functional for its intended purposes. The flaw demonstrates characteristics consistent with CWE-129 Input Validation and Output Processing, where inadequate validation of input data leads to unexpected system behavior. The vulnerability's impact extends beyond simple service interruption as it requires a complete cold start to restore normal operation, indicating a fundamental system stability issue rather than a recoverable error condition.
From an operational perspective, this vulnerability poses significant risks to industrial environments where these devices operate as critical infrastructure components. The requirement for cold start recovery means that affected systems may experience extended downtime during which production processes could be disrupted, potentially leading to substantial financial losses and safety hazards in industrial settings. The vulnerability affects devices used in process control, monitoring, and automation applications where continuous operation is essential, making this a particularly dangerous flaw in industrial control systems. The attack vector through TCP port 2404 suggests that remote exploitation is possible, meaning that attackers could potentially compromise these systems from external networks without physical access.
The security implications of CVE-2016-7987 align with ATT&CK technique T1499.004, which covers Network Denial of Service attacks targeting industrial control systems. This vulnerability demonstrates the critical need for robust input validation in embedded systems and industrial network protocols. Organizations using affected Siemens devices should implement immediate mitigation strategies including network segmentation, firewall rules to block unauthorized access to TCP port 2404, and firmware updates to Revision 08 or later versions. The vulnerability highlights the importance of maintaining current firmware versions in industrial environments and implementing proper network monitoring to detect anomalous traffic patterns that might indicate exploitation attempts. Additionally, this flaw underscores the necessity of conducting regular security assessments of industrial control systems to identify and remediate similar vulnerabilities before they can be exploited by malicious actors.