CVE-2019-1656 in Enterprise NFV Infrastructure Software
Summary
by MITRE
A vulnerability in the CLI of Cisco Enterprise NFV Infrastructure Software (NFVIS) could allow an authenticated, local attacker to access the shell of the underlying Linux operating system on the affected device. The vulnerability is due to improper input validation in the affected software. An attacker could exploit this vulnerability by sending crafted commands to the affected device. An exploit could allow the attacker to gain shell access with a nonroot user account to the underlying Linux operating system on the affected device and potentially access system configuration files with sensitive information. This vulnerability only affects console connections from CIMC. It does not apply to remote connections, such as telnet or SSH.
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Analysis
by VulDB Data Team • 07/03/2023
The vulnerability identified as CVE-2019-1656 represents a critical local privilege escalation flaw within Cisco Enterprise NFV Infrastructure Software (NFVIS) that specifically targets the Command Line Interface component. This vulnerability exists in the context of the NFVIS platform which serves as a virtualized infrastructure solution for network functions virtualization deployments. The flaw stems from inadequate input validation mechanisms within the CLI processing functionality, creating a pathway for authenticated local attackers to bypass normal access controls and gain unauthorized system access. The vulnerability is particularly concerning because it operates at a fundamental level of system interaction where legitimate administrative commands are processed, making it a prime target for exploitation by attackers who have already established some level of authentication within the system environment.
The technical exploitation of this vulnerability requires an attacker to possess valid authentication credentials for the NFVIS system and to establish a console connection through the CIMC (Cisco Integrated Management Controller) interface. The improper input validation occurs during the command processing phase where the CLI fails to properly sanitize or validate user input before executing system-level operations. When crafted malicious commands are sent through the console connection, the system's insufficient validation allows these inputs to be interpreted in unexpected ways, ultimately leading to shell access with nonroot user privileges. This access level, while not elevated to root, still provides significant system capabilities that could be leveraged for further exploitation or information gathering. The vulnerability specifically leverages the CIMC console connection pathway, which operates independently of network-based remote access protocols like SSH or telnet, making it distinct from typical remote exploitation vectors.
The operational impact of this vulnerability extends beyond simple unauthorized access, as it enables attackers to potentially read system configuration files that contain sensitive information such as network credentials, system parameters, and operational configurations. The underlying Linux operating system access provides attackers with a broader attack surface where they could modify system files, install malicious software, or conduct reconnaissance activities that could compromise the entire network infrastructure. This vulnerability particularly affects organizations that rely heavily on NFVIS for their virtualized network services, as it creates an entry point that could be used to compromise the core infrastructure components. The fact that this vulnerability is limited to console connections through CIMC means that organizations with proper network segmentation and access controls may be partially protected, though the local administrative access remains a significant concern.
Organizations should implement multiple layers of defense to mitigate this vulnerability, beginning with immediate patching of affected NFVIS systems to address the input validation flaws. Access controls should be reviewed and strengthened to ensure that only authorized personnel have console access through CIMC, with strict audit logging implemented for all console sessions. Network segmentation strategies should be reinforced to limit the potential impact of compromised console access, and regular security assessments should be conducted to identify unauthorized access points or unusual activities in system logs. The vulnerability aligns with CWE-20, which describes improper input validation as a fundamental weakness in software design that can lead to various security issues including privilege escalation and information disclosure. From an ATT&CK framework perspective, this vulnerability maps to techniques involving privilege escalation and credential access, specifically targeting the T1068 privilege escalation and T1550 credential access tactics. Organizations should also consider implementing behavioral monitoring solutions that can detect anomalous command sequences or unusual shell access patterns that might indicate exploitation attempts.