CVE-2015-4231 in NX-OS
Summary
by MITRE
The Python interpreter in Cisco NX-OS 6.2(8a) on Nexus 7000 devices allows local users to bypass intended access restrictions and delete an arbitrary VDC s files by leveraging administrative privileges in one VDC, aka Bug ID CSCur08416.
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Analysis
by VulDB Data Team • 05/23/2022
The vulnerability described in CVE-2015-4231 represents a critical privilege escalation and arbitrary file deletion flaw within Cisco NX-OS software version 6.2(8a) running on Nexus 7000 series switches. This issue specifically affects the Python interpreter component of the operating system and enables local attackers with administrative privileges in one Virtual Device Context to bypass intended access controls and delete files from any other VDC on the same physical device. The vulnerability stems from insufficient access control mechanisms between VDCs, which are designed to provide isolated network environments within a single physical switch infrastructure. The bug ID CSCur08416 indicates this was a documented internal tracking number for Cisco's vulnerability management system, highlighting the organization's recognition of the severity and impact of this privilege escalation vector.
The technical exploitation of this vulnerability occurs through the Python interpreter's handling of file operations and access controls within the multi-virtual device context environment. When an administrator possesses administrative privileges in one VDC, they can leverage the interpreter's inadequate boundary enforcement to execute file deletion operations against resources belonging to other VDCs. This represents a fundamental failure in the virtualization isolation mechanisms that should prevent cross-contamination between different logical network segments. The vulnerability specifically targets the file system access controls implemented by the NX-OS operating system, where the Python interpreter fails to properly validate access requests across VDC boundaries. This flaw operates at the system call level where file operations are processed, bypassing the normal access control lists and permission checking mechanisms that should separate VDC environments.
The operational impact of CVE-2015-4231 extends far beyond simple file deletion capabilities, as it represents a complete breakdown in the security isolation model of the Nexus 7000 platform. An attacker who gains administrative access to one VDC can potentially compromise the entire switch infrastructure by deleting critical system files, configuration data, or even the Python interpreter itself, leading to complete system outages or unauthorized access to other network segments. This vulnerability directly violates the principle of least privilege and can enable attackers to cause denial of service conditions, data corruption, or unauthorized access to sensitive network information. The implications are particularly severe in enterprise environments where Nexus 7000 switches serve as core network infrastructure components, as the compromise of one VDC can result in cascading failures across multiple network segments that should remain isolated. The vulnerability also enables potential data exfiltration scenarios where attackers can delete files containing sensitive network configuration information or security policies.
Mitigation strategies for CVE-2015-4231 require immediate implementation of software updates and patches provided by Cisco to address the specific access control bypass vulnerability in the Python interpreter. Organizations should implement the latest NX-OS software releases that contain fixes for this vulnerability, specifically addressing the VDC isolation mechanisms and Python interpreter security controls. Network administrators should also implement strict access control policies limiting administrative privileges to only those VDCs that require them, reducing the attack surface available to potential exploiters. The implementation of network segmentation controls and monitoring systems that can detect unauthorized file deletion activities across VDC boundaries provides additional layers of protection. Security teams should also consider implementing the principle of least privilege more rigorously, ensuring that administrative accounts have access only to the specific VDCs necessary for their operational requirements. This vulnerability aligns with CWE-284, which addresses improper access control, and maps to ATT&CK technique T1068, which covers local privilege escalation through system binary manipulation. Organizations should conduct comprehensive security assessments of their NX-OS environments to identify any potential exploitation of this vulnerability and implement proper monitoring controls to detect anomalous file deletion activities across virtual device contexts.