CVE-2017-12332 in NX-OS
Summary
by MITRE
A vulnerability in Cisco NX-OS System Software patch installation could allow an authenticated, local attacker to write a file to arbitrary locations. The vulnerability is due to insufficient restrictions in the patch installation process. An attacker could exploit this vulnerability by installing a crafted patch image on an affected device. The vulnerable operation occurs prior to patch activation. An exploit could allow the attacker to write arbitrary files on an affected system as root. The attacker would need valid administrator credentials to perform this exploit. This vulnerability affects the following products running Cisco NX-OS System Software: Multilayer Director Switches, Nexus 2000 Series Fabric Extenders, Nexus 5000 Series Switches, Nexus 5500 Platform Switches, Nexus 5600 Platform Switches, Nexus 6000 Series Switches, Nexus 7000 Series Switches, Nexus 7700 Series Switches, Unified Computing System Manager. Cisco Bug IDs: CSCvf16513, CSCvf23794, CSCvf23832.
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Analysis
by VulDB Data Team • 01/25/2021
This vulnerability exists within Cisco NX-OS System Software patch installation mechanisms, representing a critical authorization and privilege escalation flaw that enables authenticated local attackers to execute arbitrary file writes on affected network devices. The vulnerability stems from insufficient input validation and access control restrictions during the patch installation process, specifically during the pre-activation phase where the system permits file creation operations without proper sanitization of user-supplied patch images. The flaw allows an attacker with valid administrator credentials to craft malicious patch files that, when installed, can write content to arbitrary locations on the target system filesystem. This represents a fundamental breakdown in the software's security model, where the patch installation process fails to enforce proper file system access controls and validation checks that should normally prevent unauthorized file creation operations.
The technical exploitation of this vulnerability occurs during the patch installation phase, where the system processes the patch image before activating it, creating a window of opportunity for attackers to manipulate the file system through crafted patch content. The vulnerability affects a broad range of Cisco networking equipment including multilayer director switches, various Nexus series switches, and unified computing system managers, indicating a widespread impact across Cisco's enterprise networking portfolio. The attacker's ability to write arbitrary files as root privileges demonstrates a severe privilege escalation vector that could enable complete system compromise. This vulnerability aligns with CWE-22 (Improper Limitation of a Pathname to a Restricted Directory) and CWE-73 (Restriction of a Pathname to a Restricted Directory) categories, as the patch installation process fails to properly restrict file system paths and operations to prevent unauthorized access to system directories. The vulnerability also maps to ATT&CK technique T1059 (Command and Scripting Interpreter) and T1068 (Exploitation for Privilege Escalation) through the exploitation of local administrative access to achieve system-level file manipulation.
The operational impact of this vulnerability extends beyond simple file creation capabilities, as successful exploitation could enable attackers to install malicious code, modify system binaries, or establish persistent backdoors within the network infrastructure. The vulnerability's presence in multiple Cisco product lines suggests a systemic weakness in the patch management system architecture that could be leveraged to compromise entire network segments. Attackers could potentially use this vulnerability to modify critical system components, create unauthorized user accounts, or install rootkits that persist across system reboots. The fact that this vulnerability operates during the pre-activation phase means that even if patch activation fails, the file creation operations have already occurred, providing attackers with multiple opportunities to establish malicious presence on the system. Organizations running affected Cisco NX-OS software should immediately implement network segmentation, disable unnecessary patch installation capabilities, and monitor for unauthorized file system modifications. The vulnerability also highlights the importance of proper input validation and privilege separation in system software, as the patch installation process should never permit arbitrary file operations without explicit validation and authorization checks that would prevent attackers from exploiting this weakness through crafted patch content.