CVE-2015-6394 in NX-OS
Summary
by MITRE
The kernel in Cisco NX-OS 5.2(9)N1(1) on Nexus 5000 devices allows local users to cause a denial of service (device crash) via crafted USB parameters, aka Bug ID CSCus89408.
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Analysis
by VulDB Data Team • 06/28/2022
The vulnerability identified as CVE-2015-6394 represents a critical local privilege escalation issue within the Cisco NX-OS operating system version 5.2(9)N1(1) running on Nexus 5000 series switches. This flaw resides in the kernel implementation and specifically targets the handling of USB parameters, creating a pathway for authenticated local users to execute a denial of service attack that results in complete device crash. The vulnerability was documented under Cisco Bug ID CSCus89408 and demonstrates a fundamental weakness in the system's input validation mechanisms for peripheral device management.
The technical exploitation of this vulnerability occurs through the manipulation of USB parameters that are processed by the kernel during device initialization or operation. When a local user with appropriate privileges crafts specific USB configuration data, the kernel fails to properly validate these parameters, leading to memory corruption or execution flow disruption. This improper handling of user-supplied input directly violates established security principles and creates a condition where malformed USB data can trigger kernel-level exceptions or buffer overflows. The vulnerability falls under the CWE-121 category of Stack-based Buffer Overflow, though the specific manifestation in this case involves kernel-level parameter processing rather than traditional stack corruption.
From an operational impact perspective, this vulnerability poses significant risks to network infrastructure reliability and availability. The Nexus 5000 series switches serve as critical components in enterprise and data center networks, functioning as core switching equipment that handles substantial traffic loads. A successful exploitation of CVE-2015-6394 can result in complete device unavailability, requiring manual intervention for recovery and potentially causing network outages that span multiple services. The local nature of the attack means that an authenticated user with minimal privileges can cause substantial disruption, making this vulnerability particularly concerning for environments where user access controls may not be strictly enforced. Network administrators must consider the potential for both accidental and intentional exploitation, as the attack vector requires only local access to the device.
The mitigation strategies for this vulnerability involve immediate deployment of Cisco's recommended security patches and software updates that address the USB parameter handling within the kernel. Organizations should implement strict access controls to limit local administrative privileges and ensure that only authorized personnel have access to device consoles. Network segmentation and monitoring solutions should be deployed to detect anomalous USB device connections that might indicate exploitation attempts. Additionally, regular vulnerability assessments and security audits should be conducted to identify similar issues in other network components. The ATT&CK framework categorizes this vulnerability under T1068 for Local Privilege Escalation and T1499 for Network Denial of Service, highlighting the multi-faceted nature of the threat. System administrators should also consider implementing device hardening measures and regularly reviewing access logs for unusual patterns that might indicate attempted exploitation of this or similar kernel-level vulnerabilities.