CVE-2018-0337 in NX-OS
Summary
by MITRE
A vulnerability in the role-based access-checking mechanisms of Cisco NX-OS Software could allow an authenticated, local attacker to execute arbitrary commands on an affected device. The vulnerability exists because the affected software lacks proper input and validation checks for certain file systems. An attacker could exploit this vulnerability by issuing crafted commands in the CLI of an affected device. A successful exploit could allow the attacker to cause other users to execute unwanted, arbitrary commands on the affected device. Cisco Bug IDs: CSCvd06339, CSCvd15698, CSCvd36108, CSCvf52921, CSCvf52930, CSCvf52953, CSCvf52976.
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Analysis
by VulDB Data Team • 02/21/2020
The vulnerability identified as CVE-2018-0337 represents a critical security flaw in Cisco NX-OS Software that undermines the integrity of role-based access control mechanisms. This weakness specifically targets the authorization framework that governs user privileges within network devices, creating a pathway for authenticated local attackers to escalate their privileges and execute arbitrary commands on affected systems. The vulnerability stems from insufficient input validation and sanitization processes within the file system handling components of the software, which fails to properly validate user-supplied data before processing. The affected Cisco NX-OS versions implement role-based access controls that should restrict user actions based on defined permissions, but this particular flaw allows malicious actors to bypass these protective measures through carefully crafted command sequences.
The technical exploitation of this vulnerability occurs through the command-line interface of the affected network device, where an authenticated attacker can manipulate input parameters to trigger the flawed validation logic. When the system processes these crafted inputs, the inadequate sanitization allows malicious commands to be interpreted and executed with elevated privileges. This particular weakness aligns with CWE-20, which describes improper input validation, and demonstrates how insufficient validation of user-supplied data can lead to privilege escalation attacks. The vulnerability affects multiple Cisco NX-OS releases and impacts devices that utilize the software's role-based access control features, making it particularly dangerous in enterprise network environments where multiple administrators may have varying levels of access rights. Attackers can leverage this flaw to execute commands that could compromise network integrity, potentially leading to unauthorized access to sensitive network resources and data.
The operational impact of this vulnerability extends beyond simple privilege escalation, as it can enable attackers to cause other legitimate users to execute unwanted commands on the affected device. This creates a scenario where malicious activity can be performed while appearing to originate from authorized user accounts, complicating forensic analysis and audit trails. Network administrators may find it difficult to detect unauthorized activities since the commands appear to be executed by legitimate users with appropriate access rights. The vulnerability affects the fundamental security model of Cisco NX-OS devices, potentially allowing attackers to modify network configurations, access sensitive data, or even establish persistent backdoors within the network infrastructure. This type of vulnerability directly impacts the CIA triad, specifically compromising the integrity and availability of network services by enabling unauthorized command execution that could disrupt normal network operations and potentially expose sensitive network information to unauthorized parties.
Organizations should implement immediate mitigations including applying the latest security patches provided by Cisco, which address the input validation deficiencies in the affected software components. Network segmentation and monitoring should be enhanced to detect anomalous command execution patterns that might indicate exploitation attempts. Access controls should be reviewed and tightened, ensuring that only essential personnel have local access to network devices, and that privilege levels are strictly enforced through proper role-based access control implementations. Security teams should also implement comprehensive logging of CLI activities and establish alerting mechanisms for suspicious command sequences that could indicate exploitation attempts. The vulnerability demonstrates the importance of robust input validation and sanitization processes in network operating systems, as outlined in various security frameworks including the NIST Cybersecurity Framework and ISO/IEC 27001 standards for information security management. Organizations should also consider implementing additional security controls such as network access control and endpoint protection solutions to provide defense-in-depth against similar vulnerabilities that could potentially exist in other network infrastructure components.