CVE-2011-0355 in 1000V Virtual Ethernet Module (vem)
Summary
by MITRE
Cisco Nexus 1000V Virtual Ethernet Module (VEM) 4.0(4) SV1(1) through SV1(3b), as used in VMware ESX 4.0 and 4.1 and ESXi 4.0 and 4.1, does not properly handle dropped packets, which allows guest OS users to cause a denial of service (ESX or ESXi host OS crash) by sending an 802.1Q tagged packet over an access vEthernet port, aka Cisco Bug ID CSCtj17451.
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Analysis
by VulDB Data Team • 10/17/2021
The vulnerability identified as CVE-2011-0355 affects Cisco Nexus 1000V Virtual Ethernet Module versions 4.0(4) SV1(1) through SV1(3b) when deployed in VMware ESX 4.0 and 4.1 environments as well as ESXi 4.0 and 4.1 platforms. This represents a critical security flaw that resides within the virtual networking infrastructure of enterprise data centers, specifically targeting the virtual Ethernet module that facilitates communication between virtual machines and physical network infrastructure. The vulnerability stems from improper handling of network packet processing within the virtualized environment, creating a pathway for malicious actors to disrupt normal operations. The issue manifests when guest operating systems send specifically crafted 802.1Q tagged packets through access vEthernet ports, which triggers a cascade of failures leading to complete system crashes. This vulnerability directly impacts the stability and availability of virtualized environments, potentially affecting thousands of virtual machines across enterprise networks.
The technical flaw within the Cisco Nexus 1000V VEM module demonstrates a classic buffer handling or packet processing error that falls under CWE-129 Input Validation and the broader category of improper handling of network packets. The vulnerability occurs during the processing of 802.1Q tagged packets which are standard VLAN tagging frames used to identify traffic belonging to specific virtual networks. When these packets are transmitted through access vEthernet ports, the VEM module fails to properly validate or process the packet structure, leading to memory corruption or system state inconsistencies. This flaw can be categorized under the ATT&CK technique T1499.004 for Network Denial of Service, as it specifically targets the network infrastructure components that maintain connectivity within virtualized environments. The system's failure to handle dropped packets correctly means that legitimate network traffic processing becomes disrupted, causing the ESX or ESXi host operating systems to crash and restart, effectively creating a denial of service condition.
The operational impact of this vulnerability extends far beyond simple service disruption, representing a significant threat to enterprise network stability and business continuity. When exploited, the vulnerability can cause complete crashes of ESX or ESXi host operating systems, forcing administrators to perform manual restarts of affected virtualization platforms. This leads to service interruptions for all virtual machines running on those hosts, potentially affecting critical business applications and services. The attack vector is particularly concerning because it requires minimal privileges from guest operating systems, making it accessible to users with limited access rights within the virtualized environment. This vulnerability essentially provides an attacker with a powerful mechanism to cause widespread disruption across virtualized infrastructure, potentially affecting multiple virtual machines simultaneously. The impact is compounded by the fact that these virtualization platforms typically serve as foundational components for enterprise computing environments, making the consequences of exploitation particularly severe.
Organizations affected by this vulnerability should implement immediate mitigations to protect their virtualized environments from exploitation. The primary recommendation involves upgrading to Cisco Nexus 1000V Virtual Ethernet Module versions that address this specific flaw, which would typically involve applying the latest patches or service packs provided by Cisco. Network administrators should also consider implementing additional monitoring and alerting mechanisms to detect unusual packet patterns that might indicate exploitation attempts. The mitigation strategy should include network segmentation to limit the scope of potential attacks and ensure that only authorized traffic can access vEthernet ports. Security teams should also review and update their incident response procedures to account for this specific vulnerability, ensuring that system administrators are prepared to handle the consequences of host crashes. Additionally, implementing proper access controls and privilege management within virtualized environments can reduce the risk of unauthorized users exploiting this vulnerability to cause denial of service conditions.