CVE-2021-31340 in SIMATIC RF166C
Summary
by MITRE • 06/09/2021
A vulnerability has been identified in SIMATIC RF166C (All versions > V1.1 and < V1.3.2), SIMATIC RF185C (All versions > V1.1 and < V1.3.2), SIMATIC RF186C (All versions > V1.1 and < V1.3.2), SIMATIC RF186CI (All versions > V1.1 and < V1.3.2), SIMATIC RF188C (All versions > V1.1 and < V1.3.2), SIMATIC RF188CI (All versions > V1.1 and < V1.3.2), SIMATIC RF360R (All versions), SIMATIC RF615R (All versions > V3.0), SIMATIC RF680R (All versions > V3.0), SIMATIC RF685R (All versions > V3.0). Affected devices do not properly handle large numbers of incoming connections. An attacker may leverage this to cause a Denial-of-Service situation.
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Analysis
by VulDB Data Team • 06/11/2021
This vulnerability affects a range of SIMATIC radio frequency devices including various models from the RF166C, RF185C, RF186C, RF186CI, RF188C, RF188CI, RF360R, RF615R, and RF685R families. These industrial automation devices operate within critical infrastructure environments where reliability and security are paramount. The vulnerability stems from improper handling of concurrent connection requests, creating a potential denial-of-service condition that could disrupt industrial control systems. This weakness represents a fundamental flaw in the device's connection management architecture, where the system fails to properly limit or process incoming connection attempts beyond a certain threshold.
The technical flaw manifests as a lack of proper connection rate limiting and resource management mechanisms within the affected devices. When subjected to a large number of simultaneous connection requests, the devices experience resource exhaustion or process handling failures that lead to service disruption. This vulnerability aligns with CWE-400, which describes improper resource management, and specifically relates to the absence of proper input validation and connection handling protocols. The devices essentially cannot gracefully handle connection flooding scenarios, making them susceptible to both accidental and intentional denial-of-service attacks that could compromise industrial operations.
The operational impact of this vulnerability extends beyond simple service disruption to potentially threaten critical industrial processes. In manufacturing environments, these radio frequency devices often serve as communication endpoints for field devices, sensors, and actuators within Siemens' industrial automation ecosystem. When affected devices become unavailable due to denial-of-service conditions, it can result in production halts, data loss, or compromised process control. The vulnerability's potential for exploitation through network-based attacks makes it particularly concerning for industrial control systems where maintaining continuous operation is essential for safety and productivity. Attackers could leverage this weakness to systematically disrupt operations or create conditions that might mask other security incidents.
Mitigation strategies should focus on implementing network-level controls and firmware updates where available. Organizations should consider deploying network segmentation to limit access to these devices and implement connection rate limiting at network boundaries. The affected devices should be monitored for unusual connection patterns that might indicate attempted exploitation. Additionally, implementing network intrusion detection systems can help identify potential exploitation attempts. According to ATT&CK framework, this vulnerability maps to T1499.004 which covers network denial of service, and T1566.001 which addresses spearphishing with social engineering. Regular security assessments and vulnerability management programs should include these devices to ensure proper patching and configuration management. The recommended approach includes disabling unnecessary services, implementing strict access controls, and maintaining detailed network monitoring to detect anomalous connection behavior that could indicate exploitation attempts.