CVE-2017-6227 in Fibre Channel SAN
Summary
by MITRE
A vulnerability in the IPv6 stack on Brocade Fibre Channel SAN products running Brocade Fabric OS (FOS) versions before 7.4.2b, 8.1.2 and 8.2.0 could allow an attacker to cause a denial of service (CPU consumption and device hang) condition by sending crafted Router Advertisement (RA) messages to a targeted system.
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Analysis
by VulDB Data Team • 01/03/2020
The vulnerability identified as CVE-2017-6227 represents a critical flaw within the IPv6 implementation of Brocade Fibre Channel SAN products that operates within the Brocade Fabric OS environment. This weakness specifically affects systems running FOS versions prior to 7.4.2b, 8.1.2, and 8.2.0, creating a significant attack surface for malicious actors seeking to disrupt network operations. The vulnerability resides in how the system processes Router Advertisement messages, which are standard IPv6 protocol elements used for network configuration and routing information dissemination. The flaw demonstrates a classic example of insufficient input validation and resource management, where the system fails to properly handle malformed or crafted RA packets that could trigger unintended behavior in the underlying network stack.
The technical exploitation of this vulnerability occurs through the deliberate transmission of specially crafted Router Advertisement messages designed to overwhelm system resources. When the affected Brocade SAN switches receive these malicious packets, the IPv6 stack implementation becomes consumed with processing these malformed messages, leading to excessive CPU utilization that can eventually result in complete system hang or unresponsiveness. The attack vector leverages the standard IPv6 neighbor discovery protocol mechanisms, specifically targeting the router advertisement functionality that is essential for IPv6 network operations. This represents a sophisticated approach to denial of service attacks that exploits legitimate network protocols rather than relying on traditional attack methods, making detection and prevention more challenging for network administrators. The vulnerability falls under CWE-129, which addresses improper validation of input boundaries, and demonstrates how seemingly benign protocol elements can become weapons when improperly handled.
The operational impact of CVE-2017-6227 extends beyond simple service disruption to potentially compromise entire storage area network infrastructures. In production environments, the denial of service condition can lead to significant business disruption as Fibre Channel SAN switches become unresponsive, affecting data access and storage operations across connected systems. The affected devices may experience complete system hangs that require manual intervention and device rebooting, resulting in extended downtime and potential data loss scenarios. Network administrators may find that standard monitoring tools become ineffective as the system becomes unresponsive, complicating incident response efforts. The vulnerability particularly affects enterprise environments where Brocade SAN switches serve as critical infrastructure components for data storage and backup operations, where even brief periods of unavailability can result in substantial financial and operational losses. This weakness also aligns with ATT&CK technique T1499.004, which describes network disruption attacks targeting system availability through resource exhaustion.
Organizations should implement immediate mitigations including upgrading to supported FOS versions that contain patches addressing this vulnerability, as well as implementing network segmentation and access control measures to limit exposure to untrusted networks. Network administrators should consider deploying intrusion detection systems that can identify and block malformed IPv6 Router Advertisement traffic, while also implementing proper network monitoring to detect unusual CPU utilization patterns. The patching strategy should be prioritized based on the criticality of affected systems within the network infrastructure, with immediate attention given to switches handling mission-critical storage operations. Additional defensive measures include implementing IPv6 filtering rules at network boundaries to prevent unauthorized RA messages from reaching target systems, and conducting regular vulnerability assessments to identify other potentially affected components within the SAN infrastructure. Organizations should also develop incident response procedures specifically addressing this type of denial of service attack to ensure rapid recovery and minimize business impact during potential exploitation events.