CISA has issued a cybersecurity advisory about a denial-of-service vulnerability in Siemens SIMATIC S7-200 SMART devices, identified as CVE-2024-43647. This vulnerability, due to uncontrolled resource consumption, occurs when the affected devices mishandle TCP packets with an incorrect structure. An unauthenticated attacker can exploit this flaw to cause a disruption in the device’s operations. Once exploited, the affected device will enter a denial-of-service state, requiring a manual reset by unplugging and re-plugging the network cable to restore normal function. Siemens has rated the vulnerability with a CVSS v4 score of 8.7, indicating a high level of risk.
The vulnerability affects several versions of Siemens SIMATIC S7-200 SMART CPUs, including models CR40, CR60, SR20, SR30, ST20, and ST30, among others. This flaw exposes these devices, commonly used in industrial control systems, to potential remote exploitation. The vulnerability highlights the risk posed by improperly handled network traffic in critical systems and reinforces the need for proactive security measures to prevent attacks. Siemens has also provided mitigation guidelines to help reduce the risk of exploitation, urging users to take action immediately to secure affected devices.
To mitigate this vulnerability, Siemens recommends that organizations limit network access to trusted users and systems only. They should follow Siemens’ operational guidelines for industrial security and ensure that their devices are configured in a secure IT environment. CISA has also recommended additional defense strategies, including using firewalls to isolate control systems from business networks and applying VPNs for secure remote access. Furthermore, organizations are advised to perform thorough risk assessments and impact analysis before deploying any defensive measures, in order to understand the potential risks and ensure the security of their network.
CISA and Siemens have emphasized that no public exploitation of this vulnerability has been reported at the time of the advisory’s publication. However, given the critical nature of the vulnerability and the widespread deployment of the affected devices, it is important for organizations to implement defensive measures promptly. CISA continues to encourage organizations to adopt comprehensive cybersecurity strategies for industrial control systems and to report any suspicious activity related to the exploitation of this vulnerability.
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