CVE-2013-1211 in NX-OS
Summary
by MITRE
Cisco NX-OS on the Nexus 1000V does not properly handle authentication for Virtual Ethernet Module (VEM) to Virtual Supervisor Module (VSM) communication, which allows remote attackers to obtain VEM access via (1) spoofed STUN packets or (2) a crafted VMware ESXi instance, aka Bug ID CSCud14832.
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Analysis
by VulDB Data Team • 05/04/2019
The vulnerability identified as CVE-2013-1211 affects Cisco NX-OS software running on Nexus 1000V virtual switches, specifically targeting the authentication mechanisms between Virtual Ethernet Modules and Virtual Supervisor Modules. This weakness stems from insufficient verification processes during the communication handshake between these critical virtual components, creating a significant security gap that adversaries can exploit to gain unauthorized access to the Virtual Ethernet Module. The flaw manifests in the improper handling of authentication tokens and session validation, allowing malicious actors to bypass the established security controls that should prevent unauthorized communication between the VEM and VSM components.
The technical implementation of this vulnerability occurs through two primary attack vectors that leverage different aspects of the virtualization environment. The first vector involves spoofed STUN (Session Traversal Utilities for NAT) packets that can manipulate the authentication process by presenting false network identification information to the VSM, effectively tricking it into accepting unauthorized VEM connections. The second attack vector exploits a crafted VMware ESXi instance that can manipulate the underlying hypervisor to establish unauthorized communication channels with the VSM, bypassing the normal authentication protocols that should validate the legitimacy of VEM requests. Both attack methods rely on the fundamental weakness in the authentication framework that fails to properly validate the source identity and session integrity.
The operational impact of this vulnerability extends beyond simple unauthorized access, as it provides attackers with potential control over the virtual network infrastructure managed by the Nexus 1000V. Once an attacker gains VEM access, they can potentially manipulate virtual network configurations, intercept traffic, or establish persistent access points within the virtualized network environment. This vulnerability particularly affects enterprise data centers and cloud environments that rely on Cisco Nexus 1000V for virtual network management, as it undermines the security boundaries that separate different network segments and protect virtualized resources from unauthorized access.
Organizations utilizing Cisco Nexus 1000V deployments should implement immediate mitigations including network segmentation to isolate VEM-VSM communication channels, enhanced monitoring of STUN traffic patterns, and verification of VMware ESXi instances for unauthorized modifications. The vulnerability aligns with CWE-287, which addresses improper authentication issues in network protocols, and relates to ATT&CK technique T1078 for valid accounts and T1566 for spearphishing with social engineering. Network administrators should also consider implementing additional authentication layers, such as certificate-based authentication for VEM-VSM communications, and regularly review virtual machine configurations to detect any unauthorized modifications that might enable this attack vector. The security implications require immediate attention as the vulnerability could enable attackers to establish persistent access to virtual network infrastructure and potentially escalate privileges within the virtualized environment.