CVE-2018-11458 in SINUMERIK 828D
Summary
by MITRE
A vulnerability has been identified in SINUMERIK 828D V4.7 (All versions < V4.7 SP6 HF1), SINUMERIK 840D sl V4.7 (All versions < V4.7 SP6 HF5), SINUMERIK 840D sl V4.8 (All versions < V4.8 SP3). The integrated VNC server on port 5900/tcp of the affected products could allow a remote attacker to execute code with privileged permissions on the system by sending specially crafted network requests to port 5900/tcp. Please note that this vulnerability is only exploitable if port 5900/tcp is manually opened in the firewall configuration of network port X130. The security vulnerability could be exploited by an attacker with network access to the affected devices and port. Successful exploitation requires no privileges and no user interaction. The vulnerability could allow an attacker to compromise confidentiality, integrity and availability of the VNC server. At the time of advisory publication no public exploitation of this security vulnerability was known.
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Analysis
by VulDB Data Team • 06/18/2023
This vulnerability exists within Siemens SINUMERIK industrial control systems, specifically affecting models 828D V4.7, 840D sl V4.7, and 840D sl V4.8 with versions prior to their respective service pack and hotfix releases. The flaw resides in the integrated Virtual Network Computing VNC server that operates on port 5900/tcp, representing a critical security weakness that enables remote code execution with privileged system permissions. The vulnerability stems from inadequate input validation and authentication mechanisms within the VNC implementation, creating an attack surface that allows malicious actors to gain unauthorized access to industrial control systems. This represents a significant concern for operational technology environments where system integrity and security are paramount.
The technical exploitation of this vulnerability requires an attacker to send specially crafted network requests to the designated port 5900/tcp, which serves as the communication channel for the VNC server. The attack vector is particularly dangerous because it requires no user interaction and can be executed with network access to the affected devices. The vulnerability is classified under CWE-20 as "Improper Input Validation" and aligns with ATT&CK technique T1071.004 for application layer protocol communication. The attack chain involves an unauthenticated remote attacker who can leverage the VNC server's weaknesses to execute arbitrary code with elevated privileges, effectively bypassing normal security controls that protect industrial control systems from unauthorized access.
The operational impact of this vulnerability extends beyond simple remote code execution, as it compromises the fundamental security principles of confidentiality, integrity, and availability. An attacker who successfully exploits this vulnerability can manipulate industrial processes, access sensitive operational data, and potentially cause physical damage to manufacturing equipment. The vulnerability's impact is particularly severe in environments where industrial control systems are connected to corporate networks, as it could serve as a foothold for lateral movement attacks. The compromised VNC server could provide attackers with persistent access to critical manufacturing processes, potentially leading to production disruptions, quality control issues, and unauthorized modifications to operational parameters. This vulnerability directly affects the integrity of industrial control systems and represents a significant risk to industrial cybersecurity frameworks.
Mitigation strategies for this vulnerability include immediate implementation of firewall rules to block access to port 5900/tcp from unauthorized networks, particularly when the port is manually opened in firewall configurations. Organizations should ensure that affected systems are updated to the latest service packs and hotfixes, specifically V4.7 SP6 HF1 for 828D, V4.7 SP6 HF5 for 840D sl V4.7, and V4.8 SP3 for 840D sl V4.8. Network segmentation should be implemented to isolate industrial control systems from general corporate networks, reducing the attack surface available to potential attackers. Additionally, organizations should conduct thorough network scans to identify any unauthorized VNC server implementations and disable unnecessary remote access services. The vulnerability's exploitation requires no privileged access or user interaction, making it particularly dangerous and emphasizing the importance of proactive network security measures. Security monitoring should be enhanced to detect unusual network traffic patterns on port 5900/tcp and to identify potential exploitation attempts. Regular security assessments and vulnerability scanning should be conducted to identify similar weaknesses in industrial control system environments.