CVE-2017-20233 in Hirschmann HiLCOS OpenBAT
Summary
by MITRE • 04/04/2026
Hirschmann HiLCOS products OpenBAT, BAT450, WLC, BAT867 contains a firewall filtering vulnerability that fails to correctly filter IPv4 multicast and broadcast traffic when management IP address filtering is disabled, allowing configured filter rules to be bypassed. Attackers with network access can inject or observe multicast and broadcast packets that should have been blocked by the firewall.
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Analysis
by VulDB Data Team • 07/21/2026
The vulnerability identified as CVE-2017-20233 affects Hirschmann HiLCOS products including OpenBAT, BAT450, WLC, and BAT867, representing a critical firewall filtering weakness that undermines network security controls. This flaw specifically manifests when management IP address filtering is disabled, creating a pathway for unauthorized network traffic manipulation that directly violates fundamental security principles of network segmentation and access control. The vulnerability stems from improper handling of IPv4 multicast and broadcast traffic within the firewall implementation, where the system fails to properly enforce filtering rules that should normally prevent such traffic from traversing the network boundary.
The technical implementation flaw resides in the firewall's packet processing logic where multicast and broadcast packets are not adequately inspected against configured filter rules when management IP filtering is disabled. This represents a classic bypass vulnerability that aligns with CWE-284 Access Control Issues, specifically manifesting as inadequate access control enforcement within network security appliances. The vulnerability allows attackers to exploit the misconfigured firewall behavior to inject malicious multicast or broadcast traffic that would normally be blocked, effectively creating a backdoor for network reconnaissance and potential lateral movement. The flaw operates at the network layer where IPv4 multicast addresses (224.0.0.0 to 239.255.255.255) and broadcast addresses (255.255.255.255) are not properly filtered, enabling attackers to leverage these traffic types for network discovery and attack execution.
From an operational impact perspective, this vulnerability creates significant risks for industrial control systems and network infrastructure that rely on Hirschmann HiLCOS products for network security. The ability to bypass firewall rules using multicast and broadcast traffic opens opportunities for attackers to perform network reconnaissance, conduct denial of service attacks, or potentially establish persistence within network segments. Attackers can observe network traffic patterns and potentially extract sensitive information from multicast communications that should remain restricted. The vulnerability also aligns with ATT&CK technique T1046 Network Service Scanning and T1562.001 Impair Command and Control, as it enables adversaries to bypass network controls that would normally prevent such activities. Organizations utilizing these products face increased risk of insider threats or external attacks that exploit the misconfigured firewall behavior to gain unauthorized access to network resources.
Mitigation strategies for CVE-2017-20233 should prioritize immediate implementation of network segmentation controls and enhanced monitoring of multicast and broadcast traffic patterns. Organizations must ensure that management IP address filtering is properly configured and maintained, as disabling this feature creates the vulnerability window. Network administrators should implement additional traffic filtering rules that specifically target multicast and broadcast traffic at multiple network layers, including firewall rules that explicitly block these traffic types. The implementation of network intrusion detection systems and enhanced logging capabilities will help identify potential exploitation attempts. Additionally, organizations should conduct comprehensive network audits to identify all affected Hirschmann HiLCOS products and ensure that firmware updates are applied to address the underlying firewall implementation flaw. Regular security assessments should include verification of firewall rule enforcement and proper configuration of access control policies to prevent similar vulnerabilities from being introduced through configuration errors or mismanagement of network security controls.