CVE-2012-0352 in NX-OS
Summary
by MITRE
Cisco NX-OS 4.2.x before 4.2(1)SV1(5.1) on Nexus 1000v series switches; 4.x and 5.0.x before 5.0(2)N1(1) on Nexus 5000 series switches; and 4.2.x before 4.2.8, 5.0.x before 5.0.5, and 5.1.x before 5.1.1 on Nexus 7000 series switches allows remote attackers to cause a denial of service (netstack process crash and device reload) via a malformed IP packet, aka Bug IDs CSCti23447, CSCti49507, and CSCtj01991.
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Analysis
by VulDB Data Team • 05/04/2019
This vulnerability affects Cisco Nexus series switches across multiple product lines including the Nexus 1000v, 5000, and 7000 series switches. The flaw resides in the network stack processing functionality of the NX-OS operating system where specifically crafted malformed IP packets can trigger a critical system failure. The vulnerability impacts versions prior to specific patch releases including 4.2.x before 4.2(1)SV1(5.1) for Nexus 1000v series, 4.x and 5.0.x before 5.0(2)N1(1) for Nexus 5000 series, and various versions of Nexus 7000 series before their respective patch levels. The root cause involves improper input validation within the IP packet processing routines that fail to properly handle malformed packet structures. When these vulnerable switches receive specially crafted malformed IP packets, the netstack process crashes and subsequently causes the entire device to reload, resulting in complete service disruption. This vulnerability represents a classic denial of service condition that can be exploited remotely without authentication requirements, making it particularly dangerous in network environments where such switches serve as core infrastructure components.
The technical implementation of this vulnerability demonstrates a buffer overflow or parsing error within the IP packet handling code of the NX-OS system. The malformed packet structures exploit weaknesses in the packet validation logic that fails to properly sanitize incoming network traffic before processing. This type of vulnerability aligns with CWE-129 Input Validation and CWE-770 Allocation of Resources Without Limits or Throttling categories, as the system does not properly limit resource consumption during packet processing. The attack vector requires only that an attacker send malformed IP packets to the vulnerable switch, which can be accomplished from any network location that can reach the device. This remote exploit capability classifies the vulnerability under ATT&CK technique T1499.004 for Network Denial of Service, where adversaries leverage weaknesses in network infrastructure to disrupt services. The lack of authentication requirements makes this particularly concerning as any external party can potentially exploit the vulnerability without needing valid credentials.
The operational impact of this vulnerability extends beyond simple service interruption to encompass complete network infrastructure degradation. When the netstack process crashes and the device reloads, all forwarding and switching operations cease until the system recovers, which can result in significant network outages. In enterprise environments where these switches serve as core network components, the disruption can cascade across multiple systems and applications that depend on uninterrupted network connectivity. The vulnerability affects mission-critical network infrastructure where availability is paramount, and the automatic device reload means there is no opportunity for graceful degradation or failover mechanisms to prevent complete service loss. Organizations using these switches may experience extended downtime while the devices restart and re-establish network connections, potentially disrupting business operations and requiring manual intervention for recovery.
Mitigation strategies for this vulnerability require immediate implementation of the vendor-provided patches and updates for each affected product line. Organizations should prioritize updating all affected Nexus switches to the patched versions, specifically targeting the releases mentioned in the advisory including 4.2(1)SV1(5.1) for Nexus 1000v, 5.0(2)N1(1) for Nexus 5000, and the corresponding patch levels for Nexus 7000 series. Network administrators should also implement ingress filtering and access control lists to limit exposure to potentially malicious traffic, although this provides only partial protection as the vulnerability can be exploited from any network location. Monitoring network traffic for unusual patterns or malformed IP packets can help detect exploitation attempts, though this is more of a detection measure than a prevention strategy. The implementation of network segmentation and redundant switching paths can provide some resilience against complete service disruption, but the most effective solution remains the timely application of vendor security patches. Additionally, organizations should conduct thorough vulnerability assessments to identify all instances of affected hardware and ensure complete remediation across their entire network infrastructure.