CVE-2018-0475 in IOS
Summary
by MITRE
A vulnerability in the implementation of the cluster feature of Cisco IOS Software and Cisco IOS XE Software could allow an unauthenticated, adjacent attacker to trigger a denial of service (DoS) condition on an affected device. The vulnerability is due to improper input validation when handling Cluster Management Protocol (CMP) messages. An attacker could exploit this vulnerability by sending a malicious CMP message to an affected device. A successful exploit could allow the attacker to cause the switch to crash and reload or to hang, resulting in a DoS condition. If the switch hangs it will not reboot automatically, and it will need to be power cycled manually to recover.
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Analysis
by VulDB Data Team • 05/22/2023
The vulnerability identified as CVE-2018-0475 resides within the cluster feature implementation of Cisco IOS Software and Cisco IOS XE Software, presenting a significant security risk to network infrastructure devices. This weakness specifically targets the Cluster Management Protocol (CMP) message handling mechanisms, creating an exploitable condition that affects Cisco switching equipment. The vulnerability manifests when an attacker successfully manipulates the CMP message processing functions, leading to a complete disruption of network services through unauthorized denial of service conditions. The flaw represents a critical gap in the software's input validation procedures, where malformed or specially crafted CMP messages can bypass normal processing safeguards and trigger system instability. This vulnerability impacts a wide range of Cisco network devices including switches that utilize the cluster feature, making it particularly concerning for enterprise and service provider networks that rely heavily on redundant switching infrastructure.
The technical exploitation of CVE-2018-0475 requires an attacker to be physically adjacent to the target device, as the vulnerability is classified as an adjacent attack vector rather than a remote threat. This adjacency requirement stems from the nature of CMP protocol communications, which typically operate within local network segments and do not traverse traditional network boundaries. The improper input validation occurs during the processing of CMP messages, where the software fails to adequately validate message parameters and structures before attempting to process them. This validation failure allows attackers to craft malicious CMP packets that contain malformed data or unexpected message formats, which when received by the vulnerable device can cause memory corruption or state inconsistencies. The vulnerability aligns with CWE-20, which describes improper input validation as a fundamental weakness in software design, and demonstrates how inadequate sanitization of protocol inputs can lead to system crashes and complete service disruption.
The operational impact of this vulnerability extends beyond simple service interruption to potentially compromise network reliability and availability in mission-critical environments. When successfully exploited, the vulnerability can cause affected switches to either crash and automatically reload or enter a hung state that requires manual intervention. The automatic reload behavior, while providing a recovery mechanism, introduces additional downtime and potential disruption to network services during the reboot process. However, when the switch enters a hung state without automatic reboot capability, the situation becomes more severe as manual power cycling becomes necessary, requiring physical access to the device and potentially causing extended service outages. This vulnerability particularly affects network infrastructure that depends on redundant switching configurations, where the failure of a single switch can impact multiple network segments and services. The DoS condition can be sustained through repeated exploitation attempts, allowing attackers to maintain network disruption until manual intervention occurs or the device is physically accessed and restored.
Mitigation strategies for CVE-2018-0475 should focus on both immediate protective measures and long-term architectural improvements to network security. Network administrators should implement network segmentation and access controls to limit physical access to network equipment, reducing the attack surface for adjacent attackers. The deployment of network access control lists and port security measures can help prevent unauthorized devices from connecting to network segments where vulnerable switches reside. Cisco recommends applying the latest software patches and updates that address the input validation issues in CMP message handling, which directly resolves the vulnerability at its source. Additionally, monitoring and logging mechanisms should be enhanced to detect unusual CMP traffic patterns or malformed messages that could indicate exploitation attempts. The implementation of intrusion detection systems and network behavior analysis tools can provide early warning capabilities for potential attacks targeting this vulnerability. Organizations should also develop and maintain incident response procedures specifically addressing device-level DoS conditions, including protocols for manual device recovery and restoration. This vulnerability demonstrates the importance of securing network infrastructure components and implementing defense-in-depth strategies that protect against both remote and adjacent attack vectors. The attack pattern aligns with ATT&CK technique T1499.002, which covers network disruption attacks, and highlights the need for comprehensive network security controls that address multiple threat vectors including physical access and protocol-level vulnerabilities.